GEOL 102 Exam 1

How old is the Earth?

4.54 billion years old. 4.54 Ga

Scientific Method

Using observations, experiments, and calculations to explain how something works; used to find answers to questions and solutions.

Abraham Gottlob Werner

Neptunism; thought that all layered rocks(including lava flows) had been deposited from water, a universal ocean.

James Hutton

Plutonism; Father of Geology, Internal heat source, rock cycle, siccar point outcrop and unconformity.

Charles Lyell

Published principles of Geology. Championed for uniformity of processes; described how geologic features cut across rock is younger than rock itself.revolutionized geology.

Nicholas Steno

Father of Stratigraphy, recognized that not all layers of rock had formed at the same time; proposed basic principles we use today.

William Smith

English engineer; created first geologic map based largely in part on fossils; fossils occurred in predictable, vertical relation to one another.

Uniformitarianism

Observations of earth’s processes and results also apply to the past.

The oldest zircon grain was how old?

4.36 billion years old. Hadean time period.

Index fossil

exists only for a brief interval of time; considered units of study in Biostratigraphy.

Angular Unconformity

where two layers of rock meet that are inclined at different angles to one another.

Disconformity

a gap between two sedimentary layers that are parallel; erosion, but no tilting

Nonconformity

where sedimentary volcanic rocks lie directly on igneous or metamorphic rocks

Lord Kelvin

founder of thermodynamics; president of the royal society; kelvin temperature scale

Lithosphere

refers to the uppermost mantle and crust; brittle, strong and rigid. sits on top of aesthenosphere.

Asthenosphere

upper mantle; weak and plastic

Half-Life

amount of time it takes for ½ of parent isotopes to decay to a daughter

After 4 half lives how much of this parent atom would be left?

1/16

What would we not use to determine Earth’s age.

Carbon because it is the smallest half-life cycle

Is ice a mineral?

yes

Valence Electrons

outermost electrons; only electrons that are involved in chemical bonds

What is the most abundant and common mineral class in Earth’s crust?

Silicates

Non-Silicates

<5% of Earth’s crust;

Where is carbon formed?

shallow marine environment - warm temp.

Generally If a body of igneous rock is subjected to partial melting, the magma produced is expected to be ___.

more felsic than the source rock.

When you melt a rock is it more mafic or felsic in nature?

felsic

Density Formula

mass / volume

Where is peridotite found?

upper mantle

Regional Metamorphism results in__.

mountain building

Xenolith

foreign rock

How is marble formed?

limestone; contact metamorphism

What mineral has potassium?

orthoclase, k-feldspar.

What is the difference between rhyolite and granite?

environment it was in; textural and compositional comparison

Which rock is the timekeeping rock? - quartz, biotite, zircon.

zircon

What makes up most of the mantle?

olivine

Which minerals belong to the ferromagnesian group?

Augite, Hornblende, Olivine

What is the best rock to do absolute dating on?

Igneous Rock

What part of the atom holds it’s chemistry value?

protons

What is the main thing that sedimentary rocks are used for?

Paleoclimates (based upon latitudes).

Strata

Sedimentary rocks form horizontal layers

Compositional Maturity

the amount of stable minerals

Mechanical Weathering

Processes that break down a rock into smaller versions of itself

Chemical Weathering

Processes that alter the chemical makeup of a rock to form new minerals and dissolved ions.

Size order of grain size

Gravel > Sand > Silt > Clay

Breccia is found where?

near its source.

Craton

stable interior part of a continent

Reefs are in what type of environment?

warm, shallow, tropical regions.

Where would you find quartz sandstone?

beach

Transgression

Sea level rise; sedimentation during a transgression event produces an on-lap relationship, “finning up”

Regression

Sea Level Fall - “coarsing” up

If glacier ice has a higher o18 to o16 rate, what does that infer?

warmer

Oolitic limestone

They form when calcium carbonate is deposited on the surface of sand grains rolled (by waves) around on a shallow sea floor. carbon carbonate

If we see chalk, what environment can we infer?

deep sea environment

The most dominant mineral group is?

silicates 95%; non silicates : <5%

What type of rock is formed if it is all olivine?

peridotite

If you find a high temperature, but no pressure metamorphism, what type of metamorphism is it?

contact

Regional Metamorphism

happens over a large scale, mountain-building.

Contact Metamorphism

heat, that will change the rock