rock interviews with rolling stone magazine!. introduction – rocks have stories to tell –...

ROCK INTERVIEWS

With Rolling Stone

Magazine!

Introduction – Rocks have stories to tell – stories of how EARTH was

in the past. Igneous Rocks tell of volcanism, erosion,

and mountain-building

Metamorphic Rocks tell of a landscape being altered by that volcanism or mountain-building

Sedimentary Rocks tell of various types of deposition, as well as evaporation

BASALT

• DARK & HEAVY due to __________ & ______________ contained in its minerals.

• FINE-GRAINED – CRYSTALS NOT EVIDENT due to __________ _________ at Earth’s surface.

• INDICATE SEAFLOOR – UNDERWATER VOLCANISM – fairly quiet lava flow

SCORIA

LIKE BASALT, but contained more _________, which left holes as it escaped.

OBSIDIAN

VOLCANIC GLASS erupted under great _______________ on the seafloor.

RHYOLITE

LIGHT-COLORED & LIGHT IN WEIGHT due to less heavy metals,

FINE-GRAINED – CRYSTALS NOT EVIDENT due to __________ _________ at Earth’s surface.

INDICATE CONTINENTAL VOLCANISM – quiet lava flow

PUMICE

• VOLCANIC GLASS with lots of air – less dense than water!

• Indicates a VIOLENT ERUPTION

GRANITE

LIGHT-COLORED & LIGHT IN WEIGHT due to less heavy metals,

COARSE-GRAINED – CRYSTALS EASILY EVIDENT due to __________ _________ DEEP BELOW Earth’s surface.

INDICATES a BATHOLITH – the roots of a mountain range.

DIORITE

• INTERMEDIATE in COLOR and WEIGHT

COARSE-GRAINED – CRYSTALS EASILY EVIDENT due to __________ _________ DEEP BELOW Earth’s surface.

INDICATES a BATHOLITH – the roots of a mountain range.

PERIDOTITE/GABBRO

• DARK & HEAVY due to __________ & ______________ contained in its minerals.

COARSE-GRAINED – CRYSTALS EASILY EVIDENT due to __________ _________ DEEP BELOW Earth’s surface.

INDICATES a BATHOLITH – the roots of an ancient volcano.

COLUMNAR BASALT

• DARK & HEAVY due to __________ & ______________ contained in its minerals.

COARSE-GRAINED – CRYSTALS EASILY EVIDENT due to __________ _________ DEEP BELOW Earth’s surface.

INDICATES a VOLCANIC NECK – where a volcano had once stood.

Igneous Landforms

What igneous rocks would be formed at each of these places?

Metamorphism • Rocks change form due to the actions of

heat, pressure, and chemical action.

• What TWO rocks are here? What happened to change them?

SLATE

• When Shale undergoes excessive heat & Pressure, it becomes SLATE.

• Indicates a bay bottom being tranformed by MOUNTAIN-BUILDING

GNEISS

• When GRANITE undergoes excessive heat & Pressure, it becomes GNEISS

• Indicates a BATHOLITH being tranformed by MOUNTAIN-BUILDING

SCHIST

• When SLATE undergoes excessive heat & Pressure, it becomes SCHIST

• Indicates a BATHOLITH being tranformed by MOUNTAIN-BUILDING

QUARTZITE

• When SANDSTONE undergoes excessive heat & Pressure, it becomes QUARTZITE

• Indicates a BEACH being tranformed by MOUNTAIN-BUILDING

Metamorphic Aureole

Sedimentary Rocks

• Formed from… – the deposition of sediments or detritus– Evaporation of water from mineral-rich water

bodies– Biological processes

Clastic Sedimentary Rocks:

Pressed down, shaken together…

Breccia

Rough angular fragments cemented together.

Indicates a landslide

Conglomerate

Smooth pebbles cemented together.

Indicates a fast-flowing stream

Sandstone

Sand cemented together.

Can indicate a variety of former habitats:

River

Beach

Dune

Shale

Formed from mud compacted together

Indicates a former bay, backwater, delta, etc.

EXCELLENT fossil matrix due to its extremely fine-grained composition.

Organic Sedimentary Rocks

Life Rocks!

COAL

All coal is formed from drowned, buried plant material.

Indicates a former swamp or marsh.

Increasing pressure creates different grades of coal…

Peat >Lignite > Bituminous > Anthracite

Limestone

Formed in a variety of ways, but involves the CALCITE from dead sea creatures.

As such, limestone indicates a marine environment, especially coral reefs.

Another EXCELLENT fossil matrix due not only to its extremely fine-grained composition, but also to the fact that it is made up of once living material.

Chert/Flint

Formed from the microscopic silica skeletons of diatoms, etc.

Indicates a former marine environment.

Extremely hard, dense, microcrystalline.

Found as nodules within limestone beds.

Chemical Sedimentary Rocks:

The Evaporites

Rock Gypsum, Rock Salt

Both formed from desert or drought conditions preceded by flooding.

Can form huge beds that under pressure can act like magma and flow (!) forming salt domes.

Salt Domes form the vast bulk of our oil reserves in Southeast Texas.

Travertine

Calcite condenses when heated, dissolves when cooled!

Hence, CAVES, with their wet, moderate temperatures, are a perfect place for travertine to form as water slowly percolates through a cave’s fissures.

What rocks would form in these Sedimentary environments?