Question 1

You pick up a sandstone.In the rock sample you see an impression of a sea shell in the rock.This type of fossil is a ________.

Accepted Answer

A mold is a type of fossil that forms when an organism is buried in sediment and then dissolved, leaving behind an impression of its shape. In this case, the sea shell left behind an impression in the sandstone, creating a mold. A cast is formed when mineral deposits fill in the mold, creating a 3D replica of the original organism. A permineralized fossil occurs when minerals seep into the pores of the organism and fill in the spaces, preserving it in solid rock. A pseudofossil is a mineral formation that resembles a fossil but was not formed by a living organism.

Question 2

Paleontology is the study of ________.

Accepted Answer

Paleontology is the study of ancient life, including fossils of plants, animals, and other organisms. It also involves studying the evolution, behavior, and ecology of these extinct species, as well as their interactions with the environment.

Question 3

Little Johnnie from down the street from your house brings an object that looks like a bone,and Johnnie says "look,I found a dinosaur bone." Which of the following would not be useful in evaluating Johnnie's claim?

Accepted Answer

Extracting charcoal from the object and using carbon-14 dating would not be useful in evaluating Johnnie's claim as the object he found is not necessarily made of wood, which is what carbon-14 dating is useful for. The other options would help in determining the authenticity of Johnnie's claim, such as examining the hardness, location, and texture of the object.

Question 4

The Morrison Formation is exposed in the western United States and represents a nonmarine deposit with abundant dinosaur fossils.Much of the Morrison is pure mudstone,yet it is common to find highly polished pebbles and cobbles in the mud.Which of the following do you think is the best explanation of these cobbles?

Accepted Answer

Gastroliths are smooth, polished stones that were ingested by dinosaurs to help them break down tough plant material in their stomachs. As the stones rubbed against each other and the walls of the stomach, they became rounded and polished. It is common to find gastroliths in association with dinosaur fossils, especially in the Morrison Formation.

Question 5

By applying the law of superposition,________ dates can be determined.

Accepted Answer

The law of superposition is a principle in geology that states that in a sequence of sedimentary rock layers, each layer is younger than the one below it and older than the one above it. By applying this law, the relative order of the rock layers can be determined, but not the absolute age of the rocks. Therefore, only relative dates can be determined by applying the law of superposition.

Question 6

You go for a hike across an outcropping of sandstone and you see large footprints in the sandstone.You have just found ________.

Accepted Answer

Large footprints in sandstone are most likely trace fossils, which are evidence of the activities of ancient organisms such as footprints, burrows, or even feces. While Bigfoot sightings are rumored, there is no scientific evidence to support their existence. Proof of an ancient flood or a mold would not be indicated by large footprints in sandstone.

Question 7

Petrified wood is an example of a fossil formed by ________.

Accepted Answer

Petrified wood is formed through the process of permineralization, in which minerals replace the original organic material of the wood. This leads to the preservation of the wood's structure, but with minerals instead of the original cellulose.

Question 8

Who made the first clear statement of the law of superposition? When?

Accepted Answer

The law of superposition was first clearly stated by Nicolaus Steno, a Danish scientist, in the seventeenth century. Steno's work established the principle that each layer of sedimentary rock is younger than the layer beneath it, and older than the layer above it, provided that the layers have not been disturbed or deformed by geological forces.

Question 9

Which of the following is not a fossil?

Accepted Answer

None of the above are fossils because they are all examples of fossils.

Question 10

________ is an erosional contact between tilted,older strata below and horizontal,younger strata above.

Accepted Answer

This type of contact is called an angular unconformity. The older strata are tilted and eroded before the deposition of the younger, horizontal strata, creating an angular relationship between the two. Inverse bedding refers to the reversal of bedding orientation, a disconformity is a contact between parallel layers of sedimentary rock with a time gap in between, and cross cutting refers to the intrusion of igneous or metamorphic rocks into pre-existing rocks.

Question 11

A worm would stand a poor chance of being fossilized because ________.

Accepted Answer

Fossils are formed when the remains of an organism are preserved in sedimentary rock. Worms, however, have no hard parts such as bones, shells or exoskeletons. Therefore, they have a very low chance of being fossilized as there is no solid material for them to leave behind.

Question 12

Rare,but complete preservation of fossils occurs in ________.

Accepted Answer

Amber is a natural resin that hardens over millions of years, completely preserving any organisms trapped inside.

Question 13

Which of the following geologic observations would not bear directly on working out the sequence of geologic events in an area?

Accepted Answer

The feldspar and quartz contents of a granite can give information on the mineralogy of the rock but does not directly indicate the sequence of geologic events in an area. Inclusions, dikes, and unconformities all provide clues to the order of events.

Question 14

Visualize five horizontal sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers,1 being the lowest bed and 5 being the highest.Which of the following statements concerning the strata is true?

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 rocks are at the top. Therefore, bed 1 is the oldest and bed 5 is the youngest. Bed 2 must be younger than bed 1, but we don't know if it is older or younger than bed 4. Bed 3 must be younger than beds 1 and 2, so it is older than bed 4 but we don't know if it is older or younger than bed 5. Finally, we know that bed 4 is younger than beds 1 and 3, but we don't know if it is older or younger than bed 2 or bed 5. Therefore, the only statement that we can determine to be true is that beds 1 and 3 are older than bed 4.

Question 15

Which of the following organisms would be most likely to be preserved in the geologic record?

Accepted Answer

Clams with thick calcite shells that lived on mudflats are more likely to be preserved in the geologic record because their hard shells are better able to withstand the pressures and processes of fossilization. The bones of a dinosaur on semi-arid plains may not have been preserved due to exposure to the elements or scavengers, while trees and mussels are less likely to have been buried quickly enough to be preserved.

Question 16

Which of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas?

Accepted Answer

Correlation is the process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas. This allows them to create a geological map of an entire region or even the world.

Question 17

Assume that you have just examined several flat-lying sedimentary layers.After much study you determine that there is a considerable span of time for which no sedimentary rock layer exists at this site.You have just discovered a(n)________.

Accepted Answer

A considerable span of time for which no sedimentary rock layer exists at a site is indicative of a disconformity, which is a type of unconformity where there is missing rock record between parallel sedimentary layers. Angular unconformities involve non-parallel sedimentary layers and cross-cutting relationships involve the intrusion of one rock body into another. Series of conformable strata indicate the presence of layers that have been continuously deposited without interruption.

Question 18

One type of fossil that can preserve details of organic soft parts is ________.

Accepted Answer

Carbonized imprints involve the compression of soft parts of the organism onto a rock surface, creating a carbon film that can preserve details of those soft parts. Permineralization involves the infiltration of mineral-rich water into the pores of the organism's tissues, creating a mineralized replica of the organism. Casts are formed when sediments fill in the hollow space of a decomposed organism, creating a 3D mold. Coprolites are fossilized feces that may contain remains of undigested organisms. Therefore, carbonized imprints are the best choice for preserving details of organic soft parts.

Question 19

Which type of unconformity would generally indicate the greatest amount of erosion prior to deposition of the overlying rocks?

Accepted Answer

A nonconformity represents the greatest amount of erosion because it forms when sedimentary rocks are deposited on top of igneous or metamorphic rocks, indicating a significant gap in the geologic record.

Question 20

What fundamental concept states that in a horizontal sequence of conformable sedimentary strata,each higher bed is younger than the bed below it?

Accepted Answer

The law of superposition states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it. This is a fundamental concept in determining the relative ages of rocks and is used extensively in geological studies. The other choices either do not exist or are not related to this concept.

Quiz 11: Geologic Time