upper cretaceous - lower tertiary lithostratigraphic relationships of three cores from alberta,...

Upper Cretaceous – lower Tertiarylithostratigraphic relationships of threecores from Alberta, Saskatchewan, andManitoba, Canada1

D.R. Braman, A.R. Sweet, and J.F. Lerbekmo

Abstract: Cores from three stratigraphic test holes provide a relatively complete section from the lower Maastrichtianinto the Paleocene. The hole drilled in the Cypress Hills of Alberta recovered core from the Ravenscrag Formation tothe top of the Eastend Formation and demonstrated that most of the stratigraphy above the Battle Formation isassignable to the Ravenscrag Formation. The hole drilled in the Wood Mountain area of Saskatchewan recovered corefrom the Ravenscrag Formation to the Bearpaw Formation. This core helps explain the difficulty that has beenencountered subdividing the interval between the Bearpaw and Ravenscrag formations into separate formations andprovides a cored record of all the Ravenscrag coals within the Wood Mountain area. The core hole drilled at TurtleMountain, Manitoba, recovered core from the Turtle Mountain Formation to the Pierre Formation. It demonstrates thedifficulty in separating the Peace Garden and Goodlands members of the Turtle Mountain Formation, is useful as aprincipal reference section for the Coulter Member of the Pierre Formation, documents a disconformity within thePierre Formation, and crosses the obscure contact between the Coulter and Odanah members.

Résumé: Les carottes de trois trous de sondage stratigraphique documentent une coupe relativement complètes’échelonnant du Maastrichtien inférieur jusque dans le Paléocène. Les trous de sondage dans les Cypress Hills del’Alberta ont procuré des carottes allant de la Formation de Ravenscrag jusqu’au sommet de la Formation d’Eastend, etcelles-ci démontrent que la majorité des strates sus-jacentes à la Formation de Battle sont assignables à la Formationde Ravenscrag. Le trou de sondage dans la région de Wood Mountain, en Saskatchewan, a fourni des carottes de laFormation de Ravenscrag jusque dans la Formation de Bearpaw. Ces dernières aident à expliquer la difficulté qui a étérencontrée en tentant de subdiviser l’intervalle entre les formations de Bearpaw et de Ravenscrag en formationsséparées, et en outre elles procurent un registre de toutes les couches de charbon dans la Formation de Ravenscrag, dela région de Wood Mountain. Le trou de forage localisé à Turtle Mountain, au Manitoba, a livré des carottess’échelonnant de la Formation de Turtle Mountain jusqu’à la Formation de Pierre. Ces carottes, en plus de démontrerla difficulté à séparer les membres de Peace Garden et de Goodlands de la Formation de Turtle Mountain, peuvent êtreutiles comme coupe de référence principale du Membre de Coulter de la Formation de Pierre, et elles documententaussi une discordance à l’intérieur de la Formation de Pierre, et elles traversent le contact énigmatique entre lesmembres de Coulter et d’Odanah.

[Traduit par la Rédaction] Braman et al. 683

Introduction

The Canadian Continental Drilling Program Cretaceous–Tertiary (K–T) Boundary Drilling Project was designed tocontribute to the information base on the Cretaceous–Tertiary boundary in the western Canada portion of the Inte-rior Basin. Three deep (about 175 m) and three shallow (10–40 m) core holes were drilled spanning this boundary

(Fig. 1). The three deep core holes yielded core over ex-tended stratigraphic intervals and the present paper focuseson their lithostratigraphy. Observations are included fromthe three shallow holes and studies of surface exposures rel-evant to further understanding the lithostratigraphies en-countered in the core holes.

Study material

The three deep core holes (Fig. 1) dealt with in this reportinclude the following:

(1) Elkwater core hole (GSC K-T-1 Elkwater 12-4-8-3W4; 49°37′17′ ′N, 110°21′12′ ′W (NTS 72E/9)), locatedwithin Cypress Hills Provincial Park about 7 km (4.4 mi)southwest of Elkwater, Alberta. The recovered core includedportions of the Ravenscrag, Frenchman, Battle, Whitemud,and Eastend formations, and the uppermost portion of theBearpaw Formation. The core repository is at Core Research

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669

Received May 14, 1997. Accepted November 4, 1997.

D.R. Braman.2 Royal Tyrrell Museum of Palaeontology, Box7500, Drumheller, AB T0J 0Y0, Canada.A.R. Sweet.Geological Survey of Canada, 3303 – 33rdStreet NW, Calgary, AB T2L 2A7, Canada.J.F. Lerbekmo. Department of Geology, University ofAlberta, Edmonton, AB T6G 2E3, Canada.

1Geological Survey of Canada Contribution 1997043.2Corresponding author (e-mail: [email protected]).

Centre, Alberta Energy and Utilities Board, Calgary, Al-berta.

(2) Wood Mountain core hole (CCDP K-T Wood Moun-tain 13-31-1-2 W3; 49°05′15′ ′N, 106°16′15′ ′W (NTS 72G/1)), located about 6.8 km (4.2 mi) southeast of Killdeer,Saskatchewan. The recovered core included much of theRavenscrag, Frenchman, Whitemud, and Eastend formationsand a short portion of the Bearpaw Formation. The core re-pository is at Saskatchewan Energy and Mines, Regina, Sas-katchewan.

(3) Turtle Mountain core hole (CCDP K-T Turtle Moun-tain 13-17-1-23 W1; 49°02′36′ ′N, 100°31′55′ ′W (NTS62F/2)), located about 7.7 km (4.8 mi) southeast ofGoodlands, Manitoba. The recovered core included portionsof the Turtle Mountain, Boissevain, and Pierre formations.The core repository is at Manitoba Energy and Mines, Win-nipeg, Manitoba.

Copies of geophysical logs are stored at the core reposito-ries.

Cores from the three shallow core holes (Fig. 1) com-pleted during the drilling project are stored at GeologicalSurvey of Canada, Calgary, Alberta, and include the follow-ing:

(1) Frenchman Valley core hole (CCDP K-T FrenchmanValley 3-6-5-18 W3; 49°20′00′ ′N, 108°25′10′ ′W (NTS72F/8)), located 36 km south of Shaunavon, Saskatchewan.The recovered core included portions of the Ravenscrag andFrenchman formations.

(2, 3) Wood Mountain Creek core holes (CCDP K-TWood Mountain Creek #1 and #2 1-34-5-3 W3; 49°25′40′ ′N,106°19′30′ ′W (NTS 72G/8)), located 13.8 km northeast ofWood Mountain, Saskatchewan. Two duplicate core holes

were sited about 10 m apart and recovered core from por-tions of the Frenchman and Ravenscrag formations.

Additional information is drawn from outcrop studies inthe Cypress Hills, Red Deer Valley, Blackstone River, andCastle River areas of Alberta; the Frenchman Valley nearand southeast of Eastend, Wood Mountain Creek, RockCreek, Big Muddy, and Claybank areas of Saskatchewan;the Turtle Mountain area of Manitoba; and the Jordan areaof Montana. Other papers in this issue documentbiostratigraphy (Braman and Sweet 1999; McIntyre 1999;McIver 1999, magnetostratigraphy (Lerbekmo 1999), geo-chemistry (Lerbekmo et al. 1999), and basinal overviews(Catuneanu and Sweet 1999; Sweet et al. 1999) for thestratigraphic interval discussed in the present paper.

Stratigraphy

The stratigraphy will be discussed area by area in the fol-lowing sections. Formations relevant to the Elkwater andWood Mountain core holes are reviewed as part of the Cy-press Hills area discussion. Southern Manitoba nomenclatureis reviewed separately.

Cypress Hills areaThe Cypress Hills have been described as an oasis in the

middle of an arid country (Spry 1963). The name was usedby métis who travelled west to hunt and who incorrectlyidentified the jack pines of Manitoba as cypress and subse-quently also mistook the lodgepole pines in the hills for cy-press. The hills stretch from Alberta into Saskatchewan,being about 130 km long with a width not exceeding 24 kmand more commonly about 16 km. The hills are thought tohave been ice free during the glacial episodes of the Pleisto-

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670 Can. J. Earth Sci Vol. 36, 1999

Fig. 1. Locality map showing core-hole location and outcrop distribution.

cene and as such have animal and plant communities associ-ated with them that are not present elsewhere in westernCanada. Strata exposed in the hills include Bearpaw,Eastend, Whitemud, Battle, Frenchman, Ravenscrag, andCypress Hills formations. The Elkwater core hole was lo-cated southwest of Elkwater, adjacent to the highest point ofland in the hills at 500 m above surrounding prairie level.

James Hector, a geologist with the Palliser expedition, in1859 (Spry 1963) characterized the Cypress Hills as one ofthe most interesting spots in the country. Exploration in theregion continued with the boundary surveys of Dawson(1875) and regional studies by Dawson (1883) andMcConnell (1885). Subsequently, a large number of othergeological studies based mainly on outcrops have been car-ried out in the area, including the following selected ones:Dowling (1917), Dyer (1927), McLearn (1928), Williamsand Dyer (1930), Fraser et al. (1935), Russell and Landes(1940), Russell (1948, 1953a, 1953b), Furnival (1942,1946), Crockford (1951), Kupsch (1956, 1957), Zell (1965)and papers therein, Irish (1967), Byers (1969), Forester et al.(1977), Lerbekmo (1985), Leckie and Cheel (1989, 1990),Braman and Sweet (1990), and Catuneanu et al. (1995).These studies have set out the basic lithostratigraphic frame-work for the area that is illustrated in Fig. 2.

The core hole penetrated a sequence starting in the lowerCypress Hills Formation and ending in the uppermostEastend Formation. Nearby outcrops in Medicine LodgeCoulee, Thelma Creek, and a number of clay quarries pro-vide additional information on structures and stratigraphicrelationships of the Frenchman through Bearpaw interval.

Cypress Hills FormationDiscovered and described by McConnell (1885), the Cy-

press Hills Formation consists of an average of 38 m (Leckieand Cheel 1989) of well-rounded cobbles and boulders andisolated lenses of pebble gravels. The most common pebble

lithology is quartzite, with the gravels characterized aspoorly sorted, clast supported with a medium- to coarse-grained sand or gravel matrix. The pebbles and boulders arewell worn with a size range of 0.6–46 cm. Stratification ispoorly defined, consisting of horizontal beds that are 0.3–1.5 m thick and rare planar–tabular crossbeds up to 1 mthick. Its age has been identified as Eocene to Miocene(Storer and Bryant 1993), based on mammalian faunal as-semblages, although no definitive ages have been deter-mined for the gravels in the western part of the CypressHills. The basal contact is erosional with the RavenscragFormation. An interesting observation is that the contact inthe western Cypress Hills can be approximately placed usingthe presence of pine trees that appear restricted to CypressHills gravels. The pines are replaced on the Ravenscrag bedsby spruce. Outcrops in the western Cypress Hills occur assmall patches of gravel, along road cuts and in large slump-exposed scarps along the north side of the hills (Sauchynand Lemmen 1996). The source direction of the gravels is tothe southwest (Leckie and Cheel 1989). These authors con-clude that the gravels were deposited in proximal braidedfluvial environments in a semiarid climatic setting. Thecoarse grain size indicates that the fluvial channels experi-enced high-energy flows in close proximity to the source.The core hole encountered the lower 6.75 m of the forma-tion and, based on drilling difficulties and cuttings, consistedof pebble–cobble conglomerate with a sandstone matrix.

Ravenscrag FormationThe nonmarine Ravenscrag Formation was originally de-

scribed by Davis (1918) with a type section at RavenscragButte in southwestern Saskatchewan. As originally defined(Fig. 2), the formation included everything above theWhitemud Formation but has subsequently been restricted toinclude the coal-bearing Maastrichtian and Paleocene stratathat conformably overlie the Frenchman Formation

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Braman et al. 671

Fig. 2. Stratigraphic chart showing historical nomenclature for the Cypress Hills area.

(McLearn 1930; Furnival 1946). Russell (1948) concurredthat the presence of coal was a practical way of differentiat-ing the Ravenscrag from the underlying Frenchman. TheRavenscrag Formation underlies all of the Cypress Hills andoutcrops or underlies areas along the Frenchman River val-ley, in the area of Wood Mountain and areas eastward to thevicinity of Estevan (Irvine et al. 1978).

The formation consists of a thick (up to 120 m) series ofnonmarine finely bedded and interbedded, grey and buffclays and shales, silts, fine sands, and lignitic coals. Thesandstones, for the most part, are poorly indurated.Bentonitic, concretionary ironstone, hard sandstone, andconcretionary siltstone layers are present. The coal beds arenumerous and occur at various horizons within the forma-tion, although in the western Cypress Hills they are re-stricted to the lower part of the formation. In outcrop, thelower portion has an overall grey colour, and this has beentermed the “grey facies,” while the upper portion has a buffcolour and is termed the “buff facies” (Fraser et al. 1935). Inthe Elkwater and Wood Mountain core holes, this subdivi-sion is evident by the colour change from the red, yellow,and yellow-greens of the buff facies to the green-greys of thegrey facies. The contact between the two facies does mark arecognizable stratigraphical horizon, but varies vertically inthe sequence from place to place (Russell 1948).

The base of the formation is placed at the base of the low-est coal, Ferris seam in type section (Furnival 1946). Thiscontact can be disconformable or conformable. The Creta-ceous–Tertiary boundary is placed at or very near the base ofthe formation. When a boundary clay is present, it consistsof a 0.5–2 cm thick, buff to pinkish clay layer that containsshock quartz and an enriched amount of iridium (Lerbekmoet al. 1987; Bohor 1990).

Frenchman FormationThe nonmarine Frenchman Formation was defined by

Furnival (1946) as including units originally called theLower Ravenscrag Formation by McLearn (1929), with itstype area along the Frenchman River valley between thetowns of Ravenscrag and Eastend. There are two facies rec-ognized in the Frenchman Formation (Fraser et al. 1935;Russell 1948; Kupsch 1956; Chi 1966). One is characterizedby massive, fine- to coarse-grained, coarsely crossbedded,yellowish-grey or dusky yellow, clean and generally well-sorted sandstone. Concretionary masses commonly occur.The sandstones are interbedded with silt- and clay-rich lay-ers and there may be plant fragments, lignitic fossil wood,rare thin lignite beds, and iron concretions (Furnival 1946).The other facies is greenish-grey to brownish-grey bentoniticclay and shales. Interbedded in places with the clay are veryfine-grained sandstones.

The upper contact is usually conformable with theRavenscrag Formation and is placed at or near the base ofthe Ferris or correlative coal seam. It generally marks theCretaceous–Tertiary boundary, although at some localitiesthe boundary is a short distance above the base of the coal.This means that the entire Frenchman Formation is lateMaastrichtian in age. The lower contact is usuallydisconformable, but has been interpreted as conformable inKupsch (1956). In southwestern Saskatchewan, post-Battledowncutting has been attributed with bringing the base of

the Frenchman in contact with either the Whitemud,Eastend, or Bearpaw formation (Furnival 1946; but seeCatuneanu and Sweet 1999). The Frenchman Formation insouthwestern Saskatchewan ranges in thickness from 6 to75 m (Lerbekmo 1987) and has a wide geographic distribu-tion from the western Cypress Hills in Alberta across south-ern Saskatchewan to the vicinity of the Big Muddy Valley.The best exposed sections of the formation occur in south-western Saskatchewan in the Frenchman River valley be-tween the village of Ravenscrag to south of Shaunavon andin south-central Saskatchewan along Rock Creek.

Battle FormationFurnival (1946) first defined the unit and Irish (1970) des-

ignated a type section on the north face of Eagle Butte inquarry 45 of the Medicine Hat Brick and Tile Company inthe western Cypress Hills. Lithologically the formation con-sists of dark purplish-grey, bentonitic shale and is entirelynonmarine. The thickness is generally less than 9 m, but athickness of 14 m has been reported for the unit (Irish andHavard 1968; Binda 1970). The Battle Formation has a sin-gle or a number of ash or siliceous beds associated with itthat are referred to as the Kneehills Tuff in southern andcentral Alberta.

The upper contact is usually disconformable with theFrenchman Formation. The lower contact with theWhitemud Formation has traditionally been considered con-formable, but Catuneanu and Sweet (1999) favour adisconformable interpretation for this contact. There may bea thin interval of light-buff-weathering shales interbeddedwith the dark purple shales or a thin crossbedded unit at thebase of the formation. The base of the formation is placedwhere the dominantly dark colour of the Battle is replacedby dominantly white colouration of the Whitemud Forma-tion. The entire formation is Maastrichtian in age. The distri-bution of the formation is widespread over large areas ofsouth and central Alberta, starting as far north asWhitecourt, Alberta, and including the Red Deer River val-ley and Cypress Hills, and over areas of southwestern Sas-katchewan especially along the Frenchman River.

Whitemud FormationThe unit was first described by Davis (1918) and a type

section designated by Kupsch (1956) at Dempster’s clay pitnorthwest of Eastend, Saskatchewan. The Whitemud origi-nally included strata that are here included in the Whitemudand Battle formations. Furnival (1946) restricted the intervalreferrable to the Whitemud when he described the BattleFormation. The Whitemud Formation consists of white-weathering feldspathic sandstones, clays, and silts that aremainly smectitic on the Alberta plains or kaolinitic in Cy-press Hills and southern Saskatchewan (E.J.W. Irishin Irishand Havard 1968; Nambudiri and Binda 1991). In outcrop,the white colour makes it a readily picked marker unit. Theformation is divisible into three zones in the type area, al-though this subdivision is not always recognized elsewhere.The upper zone consists of white, kaolinitic clay; grey,mauve, and purple clays; and silts or white, kaolinitic, sandyclays in places. The middle zone consists of brown, fissile,carbonaceous shale; grey, shaly silts and clays, with thin lig-nite beds; and brown or grey kaolinitic sandstones. The

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lower zone consists of grey to white, feldspathic, kaolinitic,medium- to fine-grained sandstones with crossbedding.Binda et al. (1991) and Nambudiri and Binda (1991) indi-cate that the Whitemud represents a fining-upwards fluvialsequence that culminates in lacustrine sediments. The unit isMaastrichtian in age.

The formation is traceable across a wide area of the plainsfrom Whitecourt to Big Muddy, Saskatchewan (Worcester1950; E.J.W. Irishin Irish and Havard 1968). The thicknessof the unit is generally less than 10.5 m, but a thickness of23 m has been reported in the Eastend area (Kupsch 1956).Pruett and Murray (1991) have illustrated the Whitemud asbecoming younger to the east. The lower contact isgradational with the underlying Eastend Formation (Kupsch1956); however, Lindoe (1965) reports channelling betweenthe Whitemud and Eastend facies.

Eastend FormationFirst recognized by Russell (1932), the type section was

designated by Kupsch (1956) as one immediately southwestof Eastend, Saskatchewan. Here the formation consists ofvery fine, buff to yellowish sand and silty shale, and green-ish-grey, grey, and brown shales. The surface distribution ofthis facies extends from the eastern Cypress Hills, along theFrenchman River valley to the Wood Mountain,Willowbunch, and Regina map areas. A second Eastend fa-cies that includes carbonaceous shales, coal, and rarebentonites (Crockford 1951; Crockford and Clow 1965) isrestricted in outcrop to the Alberta portion of the CypressHills. Good exposures are available in Medicine LodgeCoulee and around Elkwater Lake.

The presence of marine bivalves (Russell 1943) anddinoflagellates indicates that the formation is in part marine.Based on the presence ofScollardia, the suggested age islate early Maastrichtian in age (Braman and Sweet 1999).The thickness is variable, but generally is between 20 and35 m; thickening from east to west in the Cypress Hills.Both upper and lower contacts are considered conformable,the lower being with the Bearpaw Formation. Only the verytop of the formation was encountered in the Cypress Hillscore hole.

Bearpaw FormationThe name was first introduced by Hatcher and Stanton

(1903), who indicated that the formation is well developedaround the Bearpaw Mountains, which is taken as the typearea. The lithology of the formation is dominated by darkgrey clays and shales with subordinate brownish-grey, siltysandstones and it is fully marine. There are numerousconcretionary beds and thin bentonites. The upper contact istransitional with the Eastend Formation in southeasternAlberta and southern Saskatchewan. The lower contact isconformable with the Dinosaur Park Formation in Albertaand western Saskatchewan. The maximum thickness of theunit is about 350 m in Saskatchewan and it decreases to adepositional edge in west-central Alberta. The formation iswidely distributed throughout central and southern Albertaand southern Saskatchewan and ranges in age from lateCampanian to early Maastrichtian in southeast Alberta andsouthern Saskatchewan. The formation was not penetrated inthe Cypress Hills core hole but was reached in the WoodMountain core hole. The formation outcrops in areas skirting

the western Cypress Hills, with good exposures present inThelma Creek and Medicine Lodge Coulee immediatelysouth of the hills. The eastern limits of the formation isplaced where the underlying Judith River Group pinches outand the Pierre Shale nomenclature is used for the completestratigraphic interval (Fig. 1).

Stratigraphic observations based on the Elkwater corehole

The Elkwater core hole has provided new information ona number of aspects of the lithostratigraphy of the western

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Braman et al. 673

Fig. 3. Annotated lithological column for the Elkwater core hole.Ages taken from Braman and Sweet (1999). lEM, late earlyMaastrichtian; eLM, early late Maastrichtian.

Cypress Hills area. The core (Fig. 3) gives, for the first time,a look at a relatively complete section of the RavenscragFormation. A number of earlier estimates of thicknesses forthe formation (Fig. 2) are too small in light of the 117 mthickness established from the core hole. Overall, theRavenscrag Formation can be subdivided into two facies.The beds from 6.8 to 29 m are varicoloured mudstones withsome dark grey interbeds probably representing paleosoils.From 29 to 122.7 m, the beds have generally grey to green-ish-grey, sombre colours. These two subdivisions wouldequate well with the buff and grey facies recognized in theRavenscrag Formation farther to the east. In contrast to theRavenscrag Formation of southern Saskatchewan, only two,very thin coals horizons were intersected in the core hole. A0.2 m thick brecciated interval at 75.0 m is unusual in tex-ture and colour compared with the rest of the stratigraphicinterval. This layer was tested for iridium, but only back-ground abundances were present. The base of theRavenscrag (Cretaceous–Tertiary boundary) was found to beunconformable with very fine-grained, yellow-greyRavenscrag sandstone overlying olive-grey Frenchmanmudstone.

The portion of the core spanning the Frenchman Forma-tion through to the top of the Eastend Formation duplicatedoutcrop sections that were studied along Medicine LodgeCoulee and in several clay quarries on the west end of theCypress Hills. The contact of the Frenchman Formation withthe Battle Formation is yellow-grey, silty mudstone overdark olive-grey to brown mudstone, which fractures into an-gular peds with slickensides. The contact between the Battleand Whitemud formations is irregular with angularWhitemud clasts in basal Battle. The Whitemud Formationis greenish-grey, silty sandstone. The Whitemud–Eastendcontact is chosen where light yellow brown-grey siltstoneoverlies light greenish-grey mudstone. The 0.2 m coal in thecored portion of the Eastend Formation is one of a numberof Eastend lignites that are present in the western CypressHills. Coal outcrops occur along Medicine Lodge Couleeand along the northern shore of Elkwater Lake, and provideindications that there are at least three coal-rich zones pres-ent in the formation. In earlier times, some of these seamswere mined near Elkwater, Alberta. To the east, when nextseen in the vicinity of Ravenscrag Butte, the Eastend Forma-tion lacks the coal facies.

Elkwater core descriptionThe Elkwater core hole reached a depth of 159.5 m; a

148.3 m interval was cored and 127 m of core recovered.Table 1 presents a description of the recovered core illus-trated in Fig. 3.

Stratigraphic observations based on the FrenchmanRiver core

A short core hole was drilled within 200 m of a knowncomplete Cretaceous–Tertiary boundary locality on the northside of the Frenchman River on the east side of Highway 37south of Shaunavon, Saskatchewan. The original intentionwas to obtain fresh material crossing the boundary. Instead,the hole penetrated a 9.2 m thick sandstone, interpreted as achannel fill, that occupied the expected position of theCretaceous–Tertiary boundary. This was not predictable

from nearby surface relationships. The hole demonstrates thepresence of Paleocene channelling that affects Maastrichtianstrata and indicates the need for care when dealing with thispart of the section.

Wood Mountain areaThe Wood Mountain upland rises 400 m above the sur-

rounding prairie and is underlain by Miocene gravels of theWood Mountain Formation that rest on the Ravenscrag For-mation. The early explorers of the plains did not penetrateinto this region, in part because it sits between the two mainroutes across the plains; the Saskatchewan River to the northand the Missouri River to the south (Rose 1916). The Indi-ans were able to maintain a strong foothold in the area untilthe latter part of the 19th century. The Hudson’s Bay Com-pany eventually established a trading post at Wood Mountainin 1868. The pace of exploration quickened over the next de-cade. Today, the area is recognized for its many uniquegeomorphic features, and this culminated in two areas withinthe hills being designated as Grasslands National Park by theCanadian Government in 1981.

Robert Bell was the first geologist to enter the WoodMountain area with his hurried trip in 1873 that provided thefirst indication of the presence of lignitic exposures in thehills (Bell 1874). A year later, G.M. Dawson crossed thearea during his study of the International Boundary. His re-port (Dawson 1875) provided the basic geological frame-work upon which most later studies were based and a recordof vertebrate fossils from the Rock Creek badlands (incor-rectly referred to as Morgan Creek by some authors). In1883–1884, R.G. McConnell examined portions of the Cy-press Hills and Wood Mountain areas. In his report,McConnell (1885) provides details of the geology, notingthe stratigraphic sequence, the coals of the Ravenscrag For-mation, and the presence of dinosaur fossils in the RockCreek badlands. Additional studies by Rose (1916), Stern-berg (1924), Fraser et al. (1935), Pearson (1962), Worcester(1950), Whitaker (1965, 1967), Irvine et al. (1978), Nicholset al. (1986), Sweet and Braman (1992), and Catuneanu etal. (1995) have established the framework for the strati-graphic sequence of the region.

The same stratigraphic nomenclature is used in the WoodMountain area as previously outlined for the Cypress Hillsarea (Fig. 4). Exposures from surrounding areas provide ex-cellent sections of the interval from the Eastend Formationinto the Ravenscrag Formation, particularly those exposureson Rock Creek, Wood Mountain Creek, and Twelve MileLake. The Wood Mountain core hole (Fig. 5) intersected thecoal-bearing Ravenscrag Formation, the Frenchman,Whitemud, and Eastend formations, before ending in theBearpaw Formation. Figure 5 provides the nomenclatureused for the numerous coals at Wood Mountain as well asnomenclature (in parentheses) that is being proposed for thesection but has yet to be formally published (B. McDougall,personal communication, 1997).

Stratigraphic observations based on the WoodMountain core hole

The cored section of the Ravenscrag Formation provides anearly complete Wood Mountain area reference section forthis formation, allowing for its subdivision into two facies:

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an upper grey-yellow facies and a lower grey facies. Thesetwo facies equate to what has been termed the buff faciesand the grey facies. The colours of the buff facies lack thevaricoloured beds seen in the Cypress Hills core and are amore uniformly yellow colour. Nineteen coals were inter-sected within the grey facies, including the formation’s basalcoal containing the Cretaceous–Tertiary boundary claystone.

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Interval (m) LithologyCypress Hills Formation

0–6.8 Pebble conglomerate, no record

Ravenscrag Formation

6.8–10.9 Yellow sandstone & green-grey mudstone, norecord

10.9–11.6 No record

11.6–14.44 Green-grey, yellow-grey to pale grey mudstone,thin limestone laminae, & dark grey to blackorganic mudstone

14.44–22.8 Mottled red & yellow to yellow-greymudstone – organic layers


25.0–26.4 Yellow-grey mudstone–limestone


27.7–28.1 Yellow-grey silty mudstone


30.0–31.1 Orange streaked, green-grey mudstone


32.2–35.0 Light olive-grey mudstone

35.0–40.0 Olive-grey to green-grey, coarse siltstone tovery fine-grained sandstone

40.0–64.94 Olive- to yellow-grey mudstone & very fine-grained to fine-grained sandstoneinterbedded – organic dark grey bands

64.94–65.01 Coal & fine-grained siltstone

65.01–75.0 Olive- to yellow-grey mudstone, siltstone &very fine-grained sandstone interbedded

75.0–75.2 Mottled red-brown breccia

75.2–79.5 Olive- to yellow-grey mudstone, siltstone &very fine-grained sandstone interbedded


79.9–90.06 Light grey to olive-grey mudstone – very fine-grained to fine-grained sandstone zones

90.06–90.13 Coal

90.13–100.5 Light grey to olive-grey mudstone – very fine-grained sandstone zones & concretionaryzones

100.5–104.0 No record

104.0–104.55 Rooted dark green-grey mudstone

104.55–105.5 No record

105.5–105.9 Rooted green-grey mudstone

105.9–106.8 No record

106.8–114.3 Yellow-grey to green-grey very fine-grainedsandstone – massive, horizontal & cross-laminated

114.3–122.7 Yellow-grey to light grey very fine-grained tomedium-grained sandstone – massive,horizontal & cross-laminated, 0.1 mconcretionary at base

Frenchman Formation

122.7–123.4 Olive-grey mudstone

123.4–123.8 No record


Table 1. Elkwater core hole lithologic log.

Interval (m) Lithology

127.0–128.4 No record

128.4–130.8 Yellow-grey to green-grey mudstone tosiltstone

130.8–132.1 Yellow-grey, fine-grained sandstone

132.1–135.5 No record

135.5–135.81 Yellow-grey mudstone

Battle Formation


141.15–141.7 No record

141.7–145.9 Dark brown to dark grey mudstone

145.9–146.5 Mottled dark brown to dark grey & green-greyvery fine-grained sandstone & mudstone

Whitemud Formation

146.5–150.7 Green-grey very fine-grained silty sandstone

Eastend Formation

150.7–155.3 Yellow-grey very fine-grained sandstone &mudstone interbedded

155.3–155.5 Coal

155.5–157.7 Yellow-grey mudstone & siltstone

157.7–158.5 No record

158.5–160.0 Light grey very fine-grained sandstone –mudstone interbedded

160.0 End of core

Table 1 (concluded).

Fig. 4. Stratigraphic chart showing historical nomenclature forsouth-central Saskatchewan area.

These coals have been subdivided into the five named coalzones shown in Fig. 5. The boundary clay is a 2 cmthickbuff-coloured layer 18 cm above the base of the lowest82 cm thick coal within the section. Therefore, by definition,the basal 18 cm of the Ravenscrag Formation isMaastrichtian at this site.

The fining-upwards, pale olive-grey sandstones of theFrenchman Formation (Fig. 5) overlie an interval of lightgreenish-yellow-grey sandstone belonging to the WhitemudFormation. Strata typical of the Battle Formation were not

observed. The light greenish-yellow-grey sandstone is un-derlain by greenish-grey silty sandstone assignable to theEastend Formation, which in turn is underlain by olive-greymarine mudstone of the Bearpaw Formation. This section re-sembles exposures in the Rock Creek badlands to the south-west of the core-hole locality. In contrast, at WoodMountain Creek, Twelve Mile Coulee, and Big Muddy tothe northwest, north, and northeast of the core hole, theFrenchman is reduced to a 1–6 m thick interval. Irvine et al.(1978) found that, based on geophysical logs alone, the in-terval between the base of the Ravenscrag and the Bearpawformations was not resolvable into separate litho-stratigraphical units east of the Cypress Hills area. This isunderstandable, given that the only visible criteria for distin-guishing formations was found to be colour and even thisdistinction was not apparent until the core dried.

Wood Mountain core descriptionThe Wood Mountain core hole reached a depth of

188.2 m, 186.1 m of section was cored, and 164 m was suc-cessively recovered. Table 2 presents a description of the re-covered core illustrated in Fig. 5.

Stratigraphic observations based on the WoodMountain Creek cores

Two short holes were drilled directly above a known Cre-taceous–Tertiary boundary site at Wood Mountain Creekwith the intention of obtaining fresh additional material fromthe stratigraphic interval spanning the boundary. The twoholes were about 10 m apart and provided duplicate coresfor the interval. Both provided samples of the boundary clay,but the surprising feature of the core was the presence of asecond tan claystone layer about 5 cm below the expectedclay layer. There is an iridium anomaly associated with boththese clay layers. The implications of the second layer arediscussed in Lerbekmo et al. (1999).

Turtle Mountain areaTurtle Mountain, Manitoba, was named for the western

painted turtle, which lives in the upland area’s many shallowlakes. The upland is about 200 m above the surroundingprairie areas and is generally heavily vegetated, with theonly bedrock exposures occurring along the north and westsides of the hills. These are very poor, limited to small,poorly exposed road cuts or along water courses.

Dawson (1875) was the first geologist to pass through thearea, but he noted no bedrock exposures and commentedonly on the glacial sediments. Tyrrell (1890) discusses theCretaceous stratigraphic section in Manitoba, includingsome brief remarks about the section in the Turtle Mountainarea. Subsequent studies by Dowling (1903a, 1903b, 1921),Kirk (1930), Wickenden (1945), Bannatyne (1970, 1978),Bamburak (1978), McNeil and Caldwell (1981), Young andMoore (1994), Kurita and McIntyre (1995), and Catuneanuet al. (1995) establish the stratigraphic sequence in and be-neath Turtle Mountain (Fig. 6).

The core hole penetrated a sequence starting in the lowerTurtle Mountain Formation and ending in the upper portionof the Odanah Member of the Pierre Formation (Fig. 7). Anumber of nearby surface sections provide little additionalinformation.

© 1999 NRC Canada


Fig. 5. Annotated lithological column for the Wood Mountaincore hole. Ages taken from Braman and Sweet (1999). lEM, lateearly Maastrichtian; eLM, early late Maastrichtian.

© 1999 NRC Canada

Braman et al. 677


Ravenscrag Formation

0–2.1 No record

2.1–3.7 Yellow to grey-yellow fine-grained to medium-grained friable sandstone

3.7–4.0 No record

4.0–7.0 Yellow to grey-yellow fine-grained to medium-grained friable sandstone

7.0–16.11 Interbedded yellow to yellow-grey mudstone &fine-grained to medium-grained sandstone – thincoal laminae

16.11–16.6 Light-grey to dark-grey mudstone

16.6–17.8 Yellow sandy siltstone


18.5–21.9 Grey-yellow mudstone & grey-yellow very fine-grained sandstone – thin coal layer


23.0–30.65 Variable-coloured yellow to grey mudstone & fine-grained to medium-grained sandstone interbedded


31.0–34.87 Grey-yellow mudstone

34.87–35.0 Coal

35.0–37.7 Grey to yellow fine-grained to medium-grainedsandstone & mudstone interbedded

37.7–38.1 Coal

38.1–40.8 Grey to yellow-grey very fine-grained sandstone &mudstone interbedded

40.8–41.2 Coal

41.2–45.1 Light grey to yellow-grey fine-grained sandstone &mudstone interbedded

45.1–46.4 Coal

46.4–58.0 Yellow-grey fine-grained to medium-grained sand-stone mudstone laminae & concretionary layer

58.0–58.9 Dark grey mudstone

58.9–59.33 Coal

59.33–59.71 Light grey mudstone

59.71–60.62 Coal

60.62–62.2 Olive-grey mudstone & fine-grained sandstoneinterbedded


62.5–63.15 Green-grey mudstone

63.15–63.46 Coal

63.46–64.75 Yellow-grey mudstone

64.75–64.82 Coal

64.82–65.7 Olive-grey very fine-grained sandstone

65.7–67.45 Coal with very fine-grained sandstone split

67.45–76.0 Green-grey mudstone & very fine-grainedsandstone interbedded – thin coal


76.8–81.0 Olive-grey to yellow-grey mudstone & very fine-grained sandstone interbedded

81.0–81.07 Coal


82.3–84.95 Dark grey to olive-grey mudstone & very fine-grained sandstone interbedded

Table 2. Wood Mountain core hole lithologic log.


84.95–85.15 Coal

85.15–85.75 Medium grey to black mudstone

85.75–89.05 Coal

89.05–93.5 Olive-grey mudstone & very fine-grainedsandstone interbedded

93.5–93.65 Coal


98.15–98.95 Coal

98.95–101.03 Olive-grey mudstone & thin coal interbedded


103.42–104.12 Coal


104.4–104.5 Coal


105.7–106.6 Coal

106.6–110.5 Green- to olive-grey mudstone & fine-grainedsandstone interbedded

110.5–110.65 Coal


110.95–111.3 Coal

111.3–115.05 Olive-grey mudstone – three thin coalsinterbedded

115.05–115.35 Coal


115.4–115.7 No record


116.6–117.5 No record

117.5–119.7 Light grey to olive-grey mudstone & medium-grained sandstone interbedded

119.7–120.74 Coal with thin boundary clayey near base coal

Frenchman Formation

120.74–121.7 Olive-grey fine-grained sandstone

121.7–123.64 No record


126.55–127.5 No record


136.9–138.0 No record

138.0–138.4 Yellow-grey fine-grained sandstone

138.4–140.15 No record

140.15–149.7 Olive-grey fine-grained sandstone

Whitemud Formation

149.7–156.75 Green-yellow fine-grained to medium-grainedsandstone

Eastend Formation

156.75–160.3 Yellow-grey fine-grained sandstone

160.3–160.8 No record

160.8–161.8 Olive-grey very fine-grained sandstone – olive-grey concretionary mudstone at base

Table 2 (continued).

Turtle Mountain FormationDowling (1921) used the terminology “Turtle Mountain

Coal Series,” but the unit was first described by Wickenden(1945). Turtle Mountain is considered the type area, al-though no particular section exists that penetrates the entireformation. Bamburak (1978) provided the most comprehen-sive discussion of the unit and gave a detailed compositesection for the formation. He subdivided the unit into twomembers, the Peace Garden and the underlying Goodlands,both of which are Paleocene in age. The maximum knownthickness of the unit is 158 m but the upper contact is every-where eroded and overlain by glacial or recent sediments.The formation overlies sandy beds of the Boissevain Forma-tion.

Peace Garden Member:The member was originally definedby Bamburak (1978) and comprises yellow-weathering, grey,silty clays with minor greenish sands and silts. The sedi-ments are poorly consolidated. A thickness of more than104 m has been indicated for the member (Bamburak 1978),and it is restricted to the immediate vicinity of Turtle Moun-tain. The lower contact is picked where the change from theunderlying bentonitic, carbonaceous, grey silty clay of theGoodlands changes to nonbentonitic, noncarbonaceous, yel-low-weathering, grey silts of the Peace Garden (Bamburak1978). The unit is marine (Bamburak 1978; Kurita andMcIntyre 1995), and was deposited during the youngest ma-rine transgression into the Western Interior of North Amer-ica. The member is laterally equivalent to the CannonballFormation of southern North Dakota (Bamburak 1978), andKurita and McIntyre (1995) suggest that the marine seawaywas a northward extension from the Gulf of Mexico, basedon their study of dinoflagellates.

Goodlands Member:The member was originally defined byBamburak (1978) and consists of grey, bentonitic, carbona-ceous sandstone, siltstone, and claystone with up to threelignite seams. In the past, the lignitic zones have been minedbut presently no mines are active. Average thickness of themember is 40 m, with its occurrence restricted to the areaaround Turtle Mountain. Much of the unit is nonmarine, al-though there are zones with marine dinoflagellates, indicat-ing periodic marine influences on the depositionalenvironments (Kurita and McIntyre 1995). The lower con-tact is placed at the base of the stratigraphically lowest lig-

nite bed or base of a dark greenish-red clay bed containingabundant plant and lignite debris.

Boissevain FormationDescribed as the Boissevain Sandstone by Parks (1916),

Wickenden (1945) formalized the name. Bamburak (1978)designated a type section for the unit southeast ofBoissevain. The formation consists of fine- to medium-grained, light-coloured sandstone with minor beds ofsiltstone and claystone. Ovoid concretionary masses with av-erage sizes of 7 m × 2 m × 1 m arecharacteristic of the unit.It also contains thin, discontinuous, in part purple-stained or-ange, ironstone layers. The formation is restricted to the Tur-tle Mountain area, where it has an average thickness of30 m. The basal contact is gradational with the fine-grainedCoulter Member and defined by Bamburak (1978, p. 6) as“at the base of the first recognizable sand bed above theclayey silt of the Coulter Member.” Much of the formation isnonmarine, but there are marine zones present in the lowerpart of the unit. Its age is middle Maastrichtian.

Pierre FormationMeek and Hayden (1862) originally proposed the name

for exposures along the Missouri River near Pierre, SouthDakota. The formation was defined as the dark grey clays ly-ing between the calcareous marl of the Niobrara Formationand the sandstones of the Fox Hills Formation. The uppercontact with the overlying Boissevain Formation in Mani-toba is gradational. The formation has been subdivided intoa number of members (McNeil and Caldwell 1981), with theCoulter and Odanah being encountered in the Turtle Moun-tain core hole. The formation is entirely marine.

Previously, two stratigraphic nomenclatures have beenproposed for the sequence in southern Manitoba. His-

© 1999 NRC Canada


Fig. 6. Stratigraphic chart showing historical nomenclature forTurtle Mountain area, Manitoba.


Bearpaw Formation

161.8–165.75 No record

165.75–166.7 Yellow-grey very fine-grained sandstone &concretions

166.7–168.85 No record

168.85–183.7 Olive-grey mudstone – minor siltstone interbedded

183.7–184.7 No record

184.7–187.4 Olive-grey mudstone – minor siltstone interbedded

187.4 End of core


torically the majority of workers and most recently Dawsonet al. (1994) have utilized the terminology of Riding Moun-tain and Vermilion River formations. However, McNeil andCaldwell (1981) have suggested that the stratigraphic sectionbetween the Niobrara equivalent (Boyne Member of theVermilion River Formation) and the Boissevain Formationshould be included in the Pierre Formation. The formationwould have the following five members in ascending order:Gammon Ferruginous, Pembina, Millwood, Odanah, and anunnamed member. The three upper members of the PierreFormation recognized by McNeil and Caldwell (1981) coin-cide with the described members of the Riding MountainFormation (Bamburak 1978; Fig. 6). In recent mapping insouthern Manitoba, the terminology of Pierre Formation hasbeen utilized (J.D. Bamburak, personal communication,1997). In this report, Pierre Formation is used to conform tothis mapping effort.

Coulter Member:Bamburak (1978) proposed this name forthe light grey to buff, fine-grained, bentonitic, siltymudstone outcropping in the Souris Valley near the town ofCoulter, Manitoba. McNeil and Caldwell (1981) did not uti-lize the Coulter Member name, but instead used the termi-nology of “unnamed member.” In part, the stated reason forthis was that no type section was identified, but Bamburak(1978) clearly states where the area of his study is and thearea near the town of Coulter, Manitoba, where outcrops oc-cur. McNeil and Caldwell’s second reason for not utilizingthe name was their feeling that there was a need to assessthe local and regional correlations. Again, Bamburak hasprovided subsurface correlations showing that the unit canbe traced between wells. Coulter Member is utilized in thepresent report. The marine Coulter ranges between 20 and55 m in thickness and its distribution is restricted to the ex-treme southwestern portion of Manitoba, including TurtleMountain. The age of the unit is Maastrichtian. The lowercontact was considered gradational and marked by the firstappearance of siliceous shale characteristic of the OdanahMember (Bamburak 1978). The core recovered during thepresent study represents the most complete section of theCoulter Member seen to date.

Odanah Member:Tyrrell (1890) named this member anddesignated exposures in the Minnedosa River valley 1 kmnorthwest of the village of Minnedosa, Manitoba, as the typearea. McNeil and Caldwell (1981) have designated alectostratotype section in a nearby railway cut. The marineunit is characterized by hard, grey, siliceous shale. Thethickness is approximately 150 m and the member occurs inthe Manitoba escarpment, underlies areas of southwesternManitoba, including the Turtle Mountain area, and has beentraced into northern North Dakota. The member ranges inage from late Campanian to early Maastrichtian.

Stratigraphic observations based on Turtle Mountaincore hole

The Turtle Mountain core hole (Fig. 7) provides the bestuppermost Cretaceous–Paleocene section from the TurtleMountain area of Manitoba recovered to date. The PeaceGarden and Goodlands members of the Turtle Mountain For-mation were both encountered in the core hole. The contact

between the members was not easily determined in the coreusing the criteria proposed by Bamburak (1978). It has beenarbitrarily placed at the base of a 20 cm pebble conglomer-ate (36.9 m), which corresponds with a colour change fromdark grey mudstones above to greenish-grey mudstones be-low. However, this leaves several intervals of marine influ-ence (Braman and Sweet 1999; McIntyre 1999) in theGoodlands Member between 36.9 and 73.8 m. There are twocoals in the Goodlands Member, one at 73.8 m and one at79.7 m, and one organic-rich mudstone, between 89.7 and

© 1999 NRC Canada

Braman et al. 679

Fig. 7. Annotated lithological column for the Turtle Mountaincore hole. Ages taken from Braman and Sweet (1999).

89.8 m. The base of the Goodlands Member is defined bythe base of the first coal or the base of a plant- and lignite-fragment-rich mudstone (Bambaruk 1978). However, sincethis organic mudstone in the core hole between 89.7 and89.8 m is of early late Maastrichtian age and strata above89.0 m are of early Paleocene age (Braman and Sweet1999), a major Cretaceous–Tertiary unconformity is presentnear the base of the Turtle Mountain Formation.

The Boissevain Formation consists of 31.3 m of sand-stone, siltstone, and mudstone in a generally coarsening up-wards succession. Although there are marine intervals in theformation, most of it appears to be nonmarine. Its lower con-tact with the Coulter Member, Pierre Formation, isgradational, as has been observed in other sections byBamburak (1978), and has been picked at the base of an in-terval where sandstone dominates (121.1 m). This is 10 mabove the base of the lowest sandstone in the cored section,a horizon that would better fit with the base of the Coulter as

© 1999 NRC Canada



Glacial Till

0–20–2 Clayey pebbly conglomerate, no record

Turtle Mountain Formation, Peace Garden Member






26.4–28.3 Yellow-grey siltstone & mudstone interbedded


29.0–32.0 Olive-grey silty mudstone

32.0–35.4 Olive-grey very fine-grained sandstone withconcretions


35.8–36.7 Dark grey fine-grained sandstone withconcretions

36.7–36.9 Light-olive-grey pebbly conglomerate

Goodlands Member

36.9–37.9 Greenblack mudstone & very fine-grainedsandstone with concretions


38.3–45.89 Olive-grey mudstone – pebbly bands

45.89–47.5 Yellow-grey very fine-grained sandstone


48.3–51.14 Yellow-grey fine-grained sandstone – organiclaminae, ripples & minor mudstone

51.14–59.55 Yellow-brown mudstone & very fine-grained tofine-grained sandstone interbedded withconcretions

59.55–60.7 Olive- to yellow-grey mudstone & very fine-grained sandstone interbedded


63.4–66.2 Yellow-grey to olive-brown mudstone & veryfine-grained sandstone interbedded


67.55–70.0 Brown-grey mudstone & very fine-grainedsandstone interbedded


71.7–73.8 Olive-grey very fine-grained sandstone, siltstone& mudstone interbedded

73.8–75.1 Coal – 8 cm mudstone split

75.1–79.4 Yellow-grey very fine-grained to fine-grainedlaminated sandstone


79.75–79.9 Coal



81.1–81.7 Olive-grey silty mudstone




Table 3. Turtle Mountain core hole lithologic log.


88.0–89.7 Olive-grey mudstone with thin limestone bed

89.7–89.8 Brown-black organic mudstone

Boissevain Formation

89.8–94.1 Light-grey fine-grained sandstone – mudstoneinterbedded near base

94.1–95.1 No recovery

95.1–97.27 Olive-grey mudstone & very fine-grainedsandstone interbedded

97.27–98.0 Olive-black mudstone

98.0–119.6 Yellow-grey to olive-brown mudstone & fine-grained sandstone interbedded

119.6–120.2 No record

120.2–121.2 Olive-brown very fine-grained sandstone

Pierre Formation, Coulter Member

121.2–122.4 No record

122.4–129.5 Variegated to olive-grey mudstone & very fine-grained sandstone laminae

129.5–131.0 Yellow- to olive-grey very fine-grainedsandstone


134.5–136.1 No record

136.1–140.2 Olive-grey siltstone & silty mudstoneinterbedded

140.2–141.9 No record

141.9–150.7 Olive-grey mudstone & siltstone interbedded

150.7–155.25 Brown to green-grey mudstone

155.25–157.5 No record


161.2–161.5 No record

161.5–166.1 Green- to olive-grey mudstone

166.1–167.5 No record

167.5–169.5 Green- to olive-grey mudstone

169.5 End of core


defined by Bamburak (1978). However, it is only an isolatedsandstone within a dominantly marine mudstone interval.

The recovered core of the Coulter Member and contigu-ous strata is the most complete section available, and wepropose it as a principal reference section for the CoulterMember. It has a thickness of 29.6 m, consists mostly of ol-ive-grey mudstone, and is entirely marine (McIntyre 1999).

The contact between the Coulter and Odanah members isinconspicuous in unweathered core. Its placement is basedmore upon a change in palynomorph assemblage and in age(Braman and Sweet 1999; McIntyre 1999) than on a con-spicuous lithological shift. The palynological break doescorrespond to a subtle downhole colour change from alighter to a darker greenish-grey, but this does not reflect themagnitude of the major hiatus (McIntyre 1999) that this con-tact represents. Drilling characteristics did not change at thiscontact.

Turtle Mountain core descriptionThe Turtle Mountain core hole reached a depth of 250 m,

150.8 m of section was cored, and 122.8 m was recovered.Table 3 presents a description of the recovered core illus-trated in Fig. 7.

Conclusions

The three longer cores have contributed new informationabout the stratigraphy in the western Cypress Hills of Al-berta, Wood Mountain area of Saskatchewan, and TurtleMountain area of Manitoba. When the lithostratigraphy iscombined with biostratigraphical, magnetostratigraphical,and geochemical information from these sections, a rela-tively complete perspective of the latest Cretaceous and Ter-tiary sequence emerges for the three areas.

The Elkwater core hole indicates that the Ravenscrag For-mation is at least 117 m thick, with a varicoloured upperportion and a somber grey lower portion. There are onlyvery thin coal zones in this formation in southeastern Al-berta. The Ravenscrag–Frenchman contact marks the Creta-ceous–Tertiary break. As the Cretaceous–Tertiary boundaryinterval is missing, the base of the lowest Ravenscrag sand-stone forms a local disconformity. The Frenchman Forma-tion is about 12 m thick in the corehole. A coal wasencountered in the uppermost part of the Eastend Formationthat is consistent with outcrop coal occurrences in surround-ing areas.

The Wood Mountain core hole provided a nearly continu-ous section through the 121 m thick Ravenscrag Formation.This unit has 19 recognized coal seams that have beenplaced in five known coal zones. The upper part of the for-mation has a dominantly yellow colour and the lower part agrey colour, which compare to the “buff” and “grey” faciesnomenclature that has been used elsewhere for the forma-tion. A well-developed boundary clay is present within thelowest coal in the core hole. This occurrence indicates that athin portion of the Ravenscrag Formation is Maastrichtianwhen Furnival’s (1946) criterion is used for picking thelower formational contact. Battle Formation strata are notpresent, whereas both the Whitemud and Eastend can beidentified.

New information was provided in the Turtle Mountaincore hole on formational and member contacts. It was not

easy picking the contacts between either the Peace Gardenand Goodlands members of the Turtle Formation, or theCoulter and Odanah members of the Pierre Shale. The picksare made on subtle lithological criteria. As interpreted here,the upper part of the Goodlands Member is marine and thelower 15 m is nonmarine and coal bearing. The core pro-vides the best section of the Coulter Member known to date,and provides an excellent reference section for the unit.

Although the cored materials have answered many ques-tions about the interval, there is still a large number of prob-lems that could benefit from additional cores, to enable afurther understanding of lateral facies changes, the presenceand duration of unconformities within the sequences studied,and the timing and extent of transgressive and regressiveevents.

Acknowledgments

Odeta Abacioaei assisted the authors with figures. LenHills, Bill McDougall, Tim Tokaryk, and Mike Dawson pro-vided critical comments on an early version of the manu-script that strengthened the final version and their efforts areappreciated. The Geological Survey of Canada, the RoyalTyrrell Museum of Palaeontology, and the University of Al-berta supported this project during all phases of its develop-ment and through to completion. Contributions by AmocoCanada Petroleum Company Ltd. and the Natural Sciencesand Engineering Research Council of Canada funded thedrilling portions of this project.

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