Astro/Geo 106 L Exam 1

Select statements true of unconformities.

1. Unconformities represent periods of erosion in the rock record. 2. Unconformities represent periods of nondeposition in the rock record. 3. There are three major types of unconformities.

Select the statement that best describes the concept of fossil succession.

There is a definite relative order in which each fossil species occurs within the layers of rock on Earth.

Uniformitarianism means

geologic processes that operate today operated in the past at about the same speed

asthenosphere

higher density and relatively soft

If a sandstone contains pieces of basalt, then the sandstone is younger than the basalt according to the principle of

inclusions

continental collision

involves continental crust

volcanic island arc

involves volcanism oceanic crust and subduction

oceanic crust

is composed of basalt and lies under a blanket of sediment

asthenosphere

is warm enough to flow slowly

Based on what you know about how fossils are created, rank the following organisms based on the likelihood that they would be preserved in the fossil record.​​​​​​​ 1. coyote 2. plantleaf 3. jellyfish 4. clam 5. fish

least likely - most likely 1. jellyfish 2. plantleaf 3. coyote 4. fish 5. clam

contact between lithospheric plates is called a

plate boundary

Which principle states that in an undisturbed sedimentary sequence, the oldest layer lies at the bottom and the youngest layer at the top?

principle of superposition

The determination that one feature is older or younger than another feature, without calculating their actual ages, is known as

relative age dating.

An area of slightly dipping sedimentary rock layers has small amounts of high-heat metamorphism adjacent to where it is intruded by an igneous dike. Using the basic principles for determining relative ages you can infer that the

sedimentary rock "baked" by the igneous intrusion is older than the intrusion.

oceanic convergence includes

subduction and volcanism

Which of the following was used as evidence by Wegener to develop the theory of continental drift?

the presence of matching mountain chains on continents currently separated by oceans

why is the lithosphere rigid while the asthenosphere is not

the temperature in the asthenosphere is higher than the lithosphere so the rock is softer

Which of the following statements are true for both the recrystallization and replacement modes of preservation?

1. Delicate tissue and organs are not preserved. 2. he three-dimensional external shape of an organism is preserved.

Identify statements true of Pangaea.

1. Rates of seafloor spreading in the Atlantic Ocean are compatible with what is known about the breakup of Pangaea. 2. The regional-scale folds visible in the Appalachian Mountains are remnants of Pangaea's formation.

Order the steps that lead to seafloor spreading.

1. The asthenosphere beneath diverging plates rises and melts. 2.A magma chamber forms beneath the ridge axis 3. Magma rises to the surface and erupts via submarine volcanoes. 4. Newly formed crust is moved laterally away from the ridge.

steps of continental volcanic arc formation

1. a subduction trench forms where the subducting plate bends downward into 2. an accretionary prism begins to form 3. magma, created by flux melting off the mantle rises through the continental lithosphere 4. lava erupts onto the surface, forming volcanoes.

order the steps of volcanic island arc formation

1. a subduction trench forms where the subjecting plate bends downward into 2. an accretionary prism begins to form 3. magma, created by flux melting of the mantle, rises through the overriding plate. 4. lava erupts onto the surface, forming volcanoes

Which of the following variables could influence the width of marine magnetic anomalies on the floor of the ocean?

1. rate at which the plates are moving away from the mid ocean ridge. 2. duration of the magnetic polarity event

Order the steps in the formation of an angular unconformity.

1. sediments are deposited and lithified 2. regional mountain building takes place and sedimentary layers are folded into anticlines synclines. 3. erosion takes place 4. sediments are deposited on top of erosional surface

order the steps in supercontinent formation and breakup

1. subduction consumes an ocean basin 2. continents collide and form a supercontinent 3. rifting takes place 4. seafloor spreading produces new lithosphere and continents move apart

identify statements true of the lithosphere and asthenosphere

1. the asthenosphere underlies the lithosphere 2. the lithosphere "floats" on the asthenosphere. 3. the asthenosphere is relatively soft compared to the rigid lithosphere.

order the steps in continental rift formation

1. the lithospheric mantle begins to stretch horizontally and thin vertically 2. The crust fractures, and faults develop. 3. large fault blocks of crust slide down into the widening rift. 4. magma erupts as lava, creating volcanoes along and near the center of the rift.

Plate tectonics theory was widely accepted by scientists in what decade?

1960's

Name the person who proposed the hypothesis of continental drift.

Alfred Wegener

The observations of _____________ led to the principle of uniformitarianism.

James Hutton

Which of the following statements about lithosphere and asthenosphere is TRUE?

Lithosphere consists of the crust and the upper mantle, and behaves like a hard layer that breaks and bends.

What is the difference between numerical age and relative age?

Numerical age gives the elapsed time between an event and the present, whereas relative age places events in sequential order.Uniformitarianism means

Plate tectonics theory took decades to be accepted because

Wegener couldn't explain how continents moved

The chain of volcanoes along the west coast of South America (the Andes Mountains) exists because

an oceanic plate is subducting under the western edge of the South American Plate.

Which type of plate boundary resulted in the formation of the West Mata volcano?

convergent

continental collision includes

crustal thickening and mountain building

lithosphere

outermost layer and relatively rigid

the center of a mid-ocean ridge is where

new oceanic lithosphere is being created

during the process of seafloor spreading

new seafloor is formed at ridges and destroyed at trenches.

An unconformity develops when

new strata are deposited atop eroded strata.