overview of indiana bedrock geology - indiana university
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Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
P. David PollyDepartment of Geological SciencesIndiana UniversityBloomington, Indiana 47405 [email protected]
Indiana bedrock geology
Overview of Indiana Bedrock Geology
Objectives
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
1. Indiana’s bedrock geological map
2. Cross-section of bedrock geology in Indiana
3. Large and small scale geological maps
4. William Smith and the first geological map
5. Stratigraphic column of Indiana
6. Stratigraphic terminology
7. David Dale Owen and geology of the Mississippi Basin
8. Overview of events represented in Indiana’s rocks
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
About geological maps
• Regions are color-coded by the age of the rocks
• Small scale maps (i.e., ones that cover large areas) are simplified by combining rock units into larger and larger age categories
• Bedrock geology consists of rock units that are lithified and extend below the surface (in most cases)
• Bedrock geology is distinguished from surficial geology, which consists of rock, dust, mud, sand, soils, and other lithic debris that has been left on the surface of the bedrock by rivers, streams, wind, glaciers, etc. Map of Indiana Showing Bedrock Geology. 1990.
Drafted by Kimberly Sowder. Indiana Geological Survey.
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Map of Indiana Showing Bedrock Geology. 1990. Drafted by Kimberly Sowder. Indiana Geological Survey.
Bedrock geological map
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Cross section (west to east) of Indiana’s major rock units
Map of Indiana Showing Bedrock Geology. 1990. Drafted by Kimberly Sowder. Indiana Geological Survey.
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Youngest (320 mya) Pennsylvanian
Oldest (360 mya) Earlier Mississippian
Edwardsville Fm. (Borden River Delta)
Salem Limestone and others (Shallow tropical seas)
Limestones Sandstones, Shales, and Coals (Nearshore seas and Terrestrial Swamps)
Bedrock Geology of Indiana. 2002. H. H. Gray (data compiler). Indiana Geological Survey.
Bedrock geology of Monroe County
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
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Canal lock in Essex, England
William Smith monument in
Churchill, England
British canals
Wm. Smith (1769-1839)
William Smith and the first geological map
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
William Smith’s 1815 Geological Map
William Smith’s Observations
• Different types of rock were not distributed randomly
• Different types of rock could be mapped as units
• If a rock unit lay on top of another in one area, it did in other areas as well
• Sedimentary rock units each had unique fossils that were not found in other units
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
19th Century canals in North America
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Indiana Geological Survey
Stratigraphic columns are the “keys” to geological maps
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
TerminologyChronostratigraphic units – units of time. Periods in the basic geological timescale are chronostratigraphic units, as are units measured in millions of years ago. From large to small these units are called eons, eras, periods, epochs, and ages. For example, “the first land plants evolved during the Silurian Period”. This sentence makes no reference to any particular rocks, only to a time in the Earth’s past.
Time-stratigraphic units – units of rock that belong to a certain time period. Groupings of rock layers based on their geological age are time-stratigraphic units. From larger to smaller these units are called systems, series, and stages. Temporal groups of rocks usually have a corresponding time unit with the same name. For example, “The Silurian System in Indiana was formed during the Siluran Era”.
Lithological units – mappable units of rocks that have similar age and the same general lithology. Groupings of rock layers as you see them in the ground. Usually rocks that are grouped together this way formed in the same environment (such as the delta of a particular ancient river). Formations are the basic lithological unit. Formations are divided into members and beds, and grouped into groups. Example, “The Borden Group contains the Edwardsville Formation and is Mississippian in age”.
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Stratigraphy in Indiana
David Dale Owen (1807-1860)
• Stratigrapher and geologist, Dale Owen was a son of Robert Owen, the socialist utopian who founded New Harmony, Indiana.
• Dale Owen conducted the first geological survey of Indiana, Kentucky, Arkansas, Iowa, Minnesota and Wisconsin
• In 1860, Owen’s museum in New Harmony was the largest west of the Appalachians.
New Harmony
Ground sloth skeleton from Owen’s Museum, shown here in it’s later home at Indiana University
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Ordovician
Silurian
Devonian
Mississippian
Pennsylvanian
Youngest (300 mya)
Oldest (470 mya)
Bedrock Geology of Indiana. 2002. H. H. Gray (data compiler). Indiana Geological Survey.
Bedrock Geology Overview
Early fishes
First land plants
First land animals
Coal swamps
Department of Geological Sciences | Indiana University(c) 2012, P. David Polly Paleontology and Geology of Indiana
Geol G-308
Glacial Till
Surficial and Bedrock Geology of Indiana. 2002. H. H. Gray (data compiler). Indiana Geological Survey.
Quaternary geology
The Quaternary
Mammal-like Reptiles
Early dinosaurs
Late dinosaurs
Early mammals
Late mammals