Question 1

Deposition of sediment with each new layer younger than the layer below illustrates the principle of

Accepted Answer

The principle of superposition states that in an undeformed sequence of sedimentary rocks, each layer of rock is younger than the one below it and older than the one above it. This is because sedimentary rocks are deposited in layers, with each new layer being added on top of previously deposited layers. Therefore, the deposition of sediment with each new layer younger than the layer below illustrates the principle of superposition.

Question 2

An eroded surface of metamorphic rocks on which a horizontal bed rests is called a

Accepted Answer

A nonconformity is an eroded surface of metamorphic or igneous rocks on which a horizontal sedimentary bed rests. This is different from a conformity, where the sedimentary layer is deposited directly on top of another sedimentary layer without any significant erosional gap or non-uniformity in between. Strata refers to distinct layers of rock, while a dike is a vertical or inclined wall-like igneous intrusion cutting through preexisting rock. A nonuniform surface is a vague term that could refer to various types of irregular or altered surfaces.

Question 3

The principle of superposition states that the top layer of rock is

Accepted Answer

The principle of superposition states that in an undisturbed sequence of sedimentary rocks, the oldest rocks are at the bottom and the youngest are at the top. Therefore, the top layer of rock is the youngest.

Question 4

Fossils are found in

Accepted Answer

Fossils are primarily found in sedimentary rocks because these rocks form from the accumulation of sediment, which can include the remains of organisms. Some metamorphic rocks, which are formed through the transformation of pre-existing rocks under the influence of high pressure and temperature, can also contain fossils if the conditions of metamorphism were not so severe as to destroy the organic remains. Igneous rocks, formed through the cooling and solidification of magma or lava, typically do not contain fossils because the high temperatures involved would destroy organic remains.

Question 5

Which relative dating principle states that in an undeformed sequence of sedimentary rocks,each layer is older than the one above and younger than the one below?

Accepted Answer

The principle of superposition states that in an undeformed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it. This is because sedimentary rocks are formed in layers with the oldest layer at the bottom and the youngest layer at the top. Therefore, option B is the correct answer.

Question 6

When comparing geologic time to a calendar year,the time of the dinosaurs is in the

Accepted Answer

If we consider the history of Earth as a calendar year, where the formation of the Earth represents January 1st and present day is December 31st, then the time of the dinosaurs, which is Mesozoic era, would fall in the second half of December. Therefore, the best choice is C, second half of December.

Question 7

A surface of erosion between rocks that represents a gap in Earth history is

Accepted Answer

An unconformity is a surface of erosion or non-deposition that represents a gap in Earth history. Dikes are intrusive igneous rocks that cut across preexisting rocks and don't necessarily represent a gap in time. Faunal conformity is not a term commonly used in geology.

Question 8

An assumption that Earth processes occurring today have always occurred is called

Accepted Answer

The assumption that Earth processes occurring today have always occurred is called uniformitarianism. This principle is fundamental in geology and implies that the same natural laws and processes observed today have been happening throughout Earth's history.

Question 9

In a sequence of rock layers we find trilobite fossils at the bottom of the rock sequence and dinosaur fossils directly above the trilobite fossils.We conclude that

Accepted Answer

This is an example of an unconformity, where erosion or other geological processes have created a gap in the rock record. The trilobite fossils are older than the dinosaur fossils, but there is no evidence that the trilobites survived up to the time of dinosaurs or that the beds are overturned. It is also unlikely that dinosaurs fed on trilobites as they are vastly different organisms from different time periods.

Question 10

The theory that different forms of animals throughout Earth's past occurred in a definite order is called the principle of

Accepted Answer

The principle of faunal succession states that different forms of animals occurred in a definite order throughout Earth's past. This principle is based on the observation that fossils found in different layers of rock can be used to determine the relative ages of those rocks.

Question 11

In a sequence of rock layers we find trilobite fossils at the bottom of rock layer 1 and dinosaur fossils directly above the fossil trilobites in layer 2.There are inclusions of trilobites in layer 2.We conclude that

Accepted Answer

The presence of trilobite fossils at the bottom of rock layer 1 and dinosaur fossils in layer 2 directly above the trilobites indicates that layer 1 is older than layer 2. The presence of trilobite inclusions in layer 2 also confirms this. This is known as the principle of faunal succession, which states that fossil organisms succeed one another in a definite and determinable order, and therefore, can be used to identify the relative ages of rock layers. The fact that there are no time gaps between the rocks is not indicated by the information given, so D is not correct. A and B are both incorrect because they contradict the known geological and paleontological records.

Question 12

An unconformity is

Accepted Answer

An unconformity is a gap in an otherwise continuous time-sequence of rock layers. It represents a period of erosion or non-deposition, and can indicate a significant change in the environment or tectonic activity.

Question 13

Sediments deposited in an even,horizontal manner illustrate the principle of

Accepted Answer

The principle of original horizontality states that sediments are generally deposited in horizontal layers, which can later become tilted or folded due to geological forces. Therefore, sediments that are deposited in an even, horizontal manner illustrate this principle. Choices A, C, and D do not address this specific principle.

Question 14

The principle of faunal succession states that

Accepted Answer

The principle of faunal succession is based on the observation that fossil organisms follow one another in a definite, irreversible time sequence. This allows geologists to use fossils to determine the relative ages of rocks and the events that occurred in the past. The other choices are not accurate statements about the principle of faunal succession.

Question 15

Conditions for the preservation of fossils are best achieved

Accepted Answer

The best conditions for the preservation of fossils are in wet environments such as shallow seas where sediment can quickly cover and protect the remains before they are destroyed. Shallow seas provide an environment that is low in oxygen and acidic, which slows the process of decay. As the sediment builds up, the pressure and heat cause it to compress into rock over time, which preserves the fossil.

Question 16

The principle of original horizontality states that each

Accepted Answer

The principle of original horizontality states that new layers of sediment are laid down nearly horizontally over older sediment. Therefore, the correct choice is C. Choices A and B are incorrect because they are inverse of each other and they both defy the principle of original horizontality. Choice D is incorrect because it is not a clear statement of the principle.

Question 17

An unconformity can be interpreted as

Accepted Answer

An unconformity is a buried surface of erosion that represents a gap in the rock record. It occurs when sedimentary rock is eroded and then new sediment is deposited on top of it. This results in a discontinuity or break in the rock sequence, representing a period of missing time. Unconformities can provide important information about past geological events and the evolution of the earth's surface. Options A, B, and D are incorrect as they do not accurately describe an unconformity.

Question 18

In a thick bed of sedimentary rocks we find an igneous dike.The order of formation is

Accepted Answer

The igneous dike cuts through the sedimentary rocks, indicating that the sedimentary layers were already present and then the igneous material intruded into these layers, solidifying later. This means the sedimentary rocks formed before the igneous dike.

Question 19

In a sequence of rock layers we find trilobite and dinosaur fossils.The dinosaur fossils are at the bottom of the rock sequence and the trilobites are at the top.This sequence tells us that

Accepted Answer

The presence of dinosaur fossils below trilobite fossils, contrary to their chronological order in the fossil record (dinosaurs appeared much later than trilobites), suggests that the rock layers have been overturned.

Question 20

In any sequence of sedimentary rock layers that have not been subjected to stress,you would expect to find

Accepted Answer

The answer of In any sequence of sedimentary rock layers...

Quiz 23: Geologic Time - Reading the Rock Record