The topography (bathymetry) of the sea floor and the magnetic polarity record in

Question

The topography (bathymetry) of the sea floor and the magnetic polarity record in sea-floor rocks are both important lines of evidence supporting Plate Tectonic Theory.

True

False

3 points   

QUESTION 38

The half-life of Uranium-235 is 713 Ma. If a crystal is analyzed for U-235 and its daughter product and the results show that one-quarter (25%) of the original U-235 atoms remain in the crystal, how long ago did the crystal form?

356 Ma

1426 Ma

2139 Ma

2852 Ma

4.57 Ga

3 points   

QUESTION 39

The boundaries between the named subdivisions of the Geologic Time Scale are placed based on _________, but not on numeric dating methods.

the variable half-life of daughter atoms

parent to daughter isotope ratios

locations of unconformities

major changes in fossils found in layered rocks

none of the above choices is correct

3 points   

QUESTION 40

Movin

Moving from the surface into the interior of the Earth, temperature ________________.

and pressure both increase

and pressure both decrease

increases, but pressure stays nearly the same

remains remarkably constant, but pressure increases.

2 points   

QUESTION 41

The average thickness of the continental crust is about

30 miles

150 miles

400 miles

10,000 miles

2 points   

QUESTION 42

The tetrahedron shaped ion group (cluster of 5 atoms) that forms the building block of all the silicate minerals is composed of silicon and what other element?

magnesium

oxygen

iron

hydrogen

2 points   

QUESTION 43

Trace amounts of impurity in a mineral can commonly produce significant differences in _____________ among individual crystals or samples of many white minerals.

color

specific gravity

hardness

luster

2 points   

QUESTION 44

The difference between lava and magma is that ______________.

magma is light in color and lava is dark

magma usually has mafic composition and lava usually has felsic composition

magma is found beneath the Earth's surface, whereas lava has reached the surface

magma flows more slowly than lava

2 points   

QUESTION 45

An eroded volcanic island that becomes submerged during sea-floor spreading is termed a ___________.

guyot

lava flow

pluton

andesite

2 points   

QUESTION 46

A dike is the name for material filling a crack in a pre-existing host rock. The general principle for assigning an older age to the host rocks relative to the dike rocks is called ____________.

superposition

fossil sequence

cross-cutting

tectonic fracturing

2 points   

QUES

356 Ma

1426 Ma

2139 Ma

2852 Ma

4.57 Ga

Explanation / Answer

Question 40: Moving from the surface into the interior of the earth, temperature ____

Answer: And pressure both increase.

Explanation: As we move into the deeper layers of the earth's core both temperature and pressure increase. Studies mention that the cores temperature maybe close to 11,000 degrees Fahrenheit.

Question 41: The average thickness of the continental crust is about ____

Answer: A. 30 MILES

Explanation: Basically the crust of earth is of two types: Oceanic and CONTINENTAL. The OCEANIC crust is 3 to 6 miles thick, where as the continental crust ranges around 30 mi thickness.

Question 42: The tetrahedron shaped ion group of silicate minerals is composed of silicon and what other element?

Answer: B. OXYGEN.

Explanation: in silica minerals structural type silica is in center and OXYGEN AT THE FOUR CORNERS.

Question 43: Trace amount of impurity in a mineral can commonly produce significant differences in ____ among individual crystals or samples of many white minerals

Answer: COLOR

Question 44: The difference between lava and magma is that ____

Answer: C. Magma is found beneath the earth's surface, where as lava has reached the surface.

Explanation: Because magma is composed of molten rock and is stored in earth's crust. Lava is simply nothing but the magma that reaches surface of earth through volcanic activity.

Question 45: An eroded volcanic island that becomes submerged during sea floor spreading is termed a ____

Answer: A. GUYOT

Explanation: Guyots are often considered as inactive volcanoes deep down on the sea floor.

Question 46: Dike general principle for assigning an older age to the host rocks relative to the dike rocks is called ____

Answer: C. CROSS-CUTTING

Explanation: In general to determine the respective ages of rocks and any other geological structures CROSS-CUTTING relations are widely used.

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