Geology ex. 2

From the center of the Earth outward to the surface, The Earth's internal are

(center) inner core, outer core, mantle, crust (surface)

Based on a mass spectrometer analysis it is determined that the parent-to-daughter ratio in a potassium feldspar crystal form a granite is one-to-one. Based on this ratio, how many half lives have elapsed since the crystal formed?

1 half life

In the Colorado National Monument, a major unconformity exists between the precambrian rocks (1.4 billlion yrs. old) and the Triassic chinle formation. The amount of geologic time represented by this gap is

1,200 mill. years old

As recorded by the rocks, Colorado's total geologic history spans

2.7 bill. years

The oldest rock in CO is approximately ___ years old

2.7 billion yrs. old

The Holocene Epoch occured during phase ____ of Colorado's geologic history

6

The Rio Grande uplift was created during phase

6

If sedimentary rocks are deformed into a lazy "s"-shaped fold the structure is called

A monocline

If sedimentary rocks are deformed into a "sag"-shaped fold (cross-sectional view), the structure is called

A syncline

Process(es) responsible for creation of a mountain belt

All of these things can create a mountain belt

If we could use a time machine to visit Colorado during phase 2 we would see

An area near sea level frequently flooded by ocean

Alaska's Aleutian Islands are an example of

An island arc

Which of the following is not a type of uniformity?

An orthoconformity

Another name for the Colorado Orogeny

Ancestral Rocky Mountains

Igneous rock type that is created by partial melting of oceanic crust in the subduction zone

Andesite

This major mountain chain formed at the same time as the Ancestral Rocky Mountains (phase 3). Today, it is found along the eastern side of North America.

Appalachian Mountains

This partly molten layer is found beneath the lithosphere.

Asthenosphere

Which statement is true?

At a subduction zone, the denser plate slides beneath the less-dense plate.

The sheet-like sandstone beds in the Mt. Garfield formation exposed along the top of the Book Cliffs are cretaceous _____ deposits

Beach

Sedimentary rocks can be age dated using a process called

Bracketing

Phase 2 of Colorado's history spans these geologic periods

Cambrian through Mississippian

This physiographic province lies west of Colorado's Rocky Mountains.

Colorado Plateau

The last time the area now known as CO was flooded by ocean water was

Cretaceous period phase 4

Diatremes in northeast Colorado contain fragments of Silurian sedimentary rocks, plus

Diamonds

The phase 2 igneous rock found near Gunnison, Colorado, that contains calcite and dolomite is called

Diorite

New oceanic crust (mafic igneous rock) is created here

Divergent plate boundaries

Numerous paleogeographic maps were shown during pro. Cole's lectures. Tthe geologist-artist who constructed these maps is

Dr. Ron Blakey, recently retired from Northern Arizona University.

Near the end of phase 6 (pleistocene Epoch), Colorado;s mountains had lots of

Glaciers

The down-dropped block between two normal faults is called a(n)

Graben

Which statement is true?

Grand Junction is in the Piceance Basin

Precambrian igneous rocks in Colorado are composed mainly of

Granite, Diorite, and pegmatite

Which of the following is not a basic type of heat transfer?

Gravity

Name for the unconformity between the Precambrian Black Canyon complex and the Triassic chinle formation in the Colorado National Monument

Great Orogeny

Denver is located on the western edge of the _____________ province

Great plains

The energy that drives the "tectonic engine" (plate movement) comes from

Heat which comes from radioactive decay of uranium

Which statement is false?

Igneous activity never occurs during an orogeny

Colorado diamonds occur in a volcanic rock called

Kimberlite

The present-day Rocky Mountains were created during the ___ Orogeny

Laramide

Which orogeny began at the end of the Cretaceous period and continued into the early tertiary period?

Laramide

Which of the following orogenies listed below is the youngest?

Laramide orogeny

Which of the following is not a physiographic province in Colorado?

Lower Rocky Mountain or Northern Rocky Mountain

This thick (-5,500 ft) interval of marine mud deposited during the Cretaceous period (phase 4) is called the

Mancos shale

This orogeny took place during the precambrian

Mazatzal

Which of the following orogenies occurred during precambrian time?

Mazatzal

Which of the following orogenies listed below is the oldest?

Mazatzal orogeny

At a convergent plate boundary, tectonic plates

Move towards each other

Which of the following statements is true?

Oceanic crust is thinner and denser than continental crust.

Term used to describe a period of mountain building in the past

Orogeny

Formation of the supercontinent ____ was the trigger for creation of the Aancestral Rocky Mountains

Pangea

In Colorado, rocks of the precambrian Era were formed during

Phase 1

Argon-40 is the radioactive decay product (daughter) of

Potassium-40

Eisenhower tunnel (I-70), which cuts through the crest of the modern-day Front Range, was excavated through this type of rock

Precambrian metamorphic and igneous rocks

The energy source that drives plate movement comes from

Primordial heat and heat from radioactive decay

Which statement is false?

Sedimentary rocks cannot be folded or fractured

This phase 4 orogeny occured in Cali, Nevada, Arizona, and Utah

Sevier

Which statement summarizes the occurrence of silurian sedimentary rocks?

Silurian sedimentary rocks are only found in diatremes of north-central Colorado.

The largest physiographic province in CO is

Southern Rocky Mountain

New oceanic crust is created here

Spreading ridges at divergent plate boundaries

Which of the following geologic principles allows a geologist to estimate the relative age of a sequence of sedimentary rocks (or a stack of pancakes)?

Superposition

Which of the following has the highest density?

The Earth's core

The Rio Grande Rift is expressed as _______ in the southern Colorado

The San Luis Valley

Regarding quantitative numerical age dates for precambrian igneous rocks in Colorado, which of the following statements is correct?

The dates occur in three groups at 1, 7,1 ,4 and 1.1 billion years ago

If we could use a time machine to visit the San Juan Mountain area during phase 6 we would see

The eruption of felsic magma from numerous volcanoes

A normal fault is defined by

The foot-wall block moving up with respect to the hanging-wall block

A reverse fault i define by

The hanging-wall block moving up with with respect to the foot-wall bock

A basalt dike cross-cuts a bed of limestone. The numeric age date of the dike is 50 million years. Which of the following statements is true?

The limestone bed is older than 50 mill. yrs.

The two sedimentary rock units are Precambrian in age

The unita Mountain and Uncompahgre groups

Which statement about Colorado's boundaries is true?

They are defined by longitude and latitude

Which of the following is the name for a thick sequence of Precambrian sedimentary rocks near Ouray, Colorado

Uncompahgre Group

This enormous uplift occupied parts of western Colorado during the Pennsylvanian-Permian periods. Gran Junction was near the crest

Uncompahgria

When an igneous rock is dated by the uranium- lead, potassium-argon or other radiometric method, the number that is obtained indicates

When the magma cooled and solidified into rock

Which sequence of orogenies (oldest to youngest) is correct?

Yavapai (oldest), Mazatzal, Ancestral Rocky Mountains, Sevier, Laramide (youngest)

The colian Wingate sandstone (Jurassic) was deposited while the climate was

hot, dry ,and windy (desert)

The Earth's core is thought to be composed mainly of

iron and nickle

By definition the rocks below a noncomformity consists of

metamorphic and or igneous rocks

If an igneous dike cross-cuts a sandstone bed, the dike is ___ the sandstone

older than