Exam I, Modules1-2; GLY1102, Sum20

If you read in a scientific article that the end of the last Ice Age was about 12 Kya, how many years ago is that?

12,000

In radioactive materials, a half-life is important to calculating the age of the material. If a sample has undergone 2 half-lives, from it's original state, how much of the original parent material is left?

25%

The oldest mineral grain on Earth was found in Australia. Radiometric dating determined the age was ____ years old.

4.4 billion

In science, a hypothesis is best described as:

An idea or question about a process or phenomenon that is used to frame a scientific research.

In science, the term "theory" is used to describe:

An idea with significant evidence to support it's validity that it is deemed a valid way to explain a process or phenomenon.

The geologic time scale is broken into progressively smaller intervals of time. From largest amount of time to smallest, the order is:

Eon, Era, Period, Epoch

True or False: The principles of stratigraphy can be used to determine the absolute age of a rock unit or fossil.

False

True or False: Radiometric dating is useful to determine the numerical age of sedimentary rocks units.

False - Correct! Radiometric dating can tell you when a crystal was first formed in magma, but it can't tell you when the sedimentary rock that eventually encased that mineral grain was formed (usually much later after erosion and transport of the grain).

According to radiometric dating techniques, the earth is about 4.6 billion years old, or 4.6 ___ using standard geologic time abbreviations.

Ga

What is commonly known as the "Age of Dinosaurs" is technically a geologic Era called the:

Mesozoic

When reading a geologic map, rock units are labeled with letter codes. The first upper-case letter indicates _______, while the following lower case letters represent ______.

The age (usually Period) in which the rock was formed, the Formation name or physical trait.

When talking about the radioactive decay of elements inside of minerals, the term "parent" and "daughter" refer to:

The original atomic nucleus and the product after it undergoes radioactive decay.

The Periods of the Mesozoic, from oldest to youngest are:

Triassic, Jurassic, Cretaceous

The fossil record is highly biased towards preservation of organisms with hard parts like bones and shells.

True

True or false: A great deal of information about an organism is lost between the time an organism dies and the time it is discovered by as a fossil millions of years later.

True

True or false: Biostratigraphy can be used to correlate the ages of rock on different continents.

True

True or false: Our understanding of dinosaurs is still evolving.

True! New studies change or update what we understand about dinosaurs all the time.

One of the fundamental principles of geology is that basic physical laws of nature, such as how elements bond and what happens to a rock left out in the rain, were the same in the past as they are today. This idea gained credibility under the name:

Uniformitarianism

Biostratigraphy is the process of using "index fossils" to determine the age of a rock unit. An ideal index fossil comes from organisms that had:

a broad geographic distribution, but a short time from appearance to extinction in the fossil record.

If a dinosaur fossil were found in a sandstone with coarse and poorly sorted grains that included the mineral feldspar, what type of environment likely existed at that location at the time that dinosaur was alive?

a desert

An impression left behind by an organism being pressed into soft sediment is called a mold. When minerals fill that void, the resulting fossil is called a ______ fossil.

a reverse mold

Dinosaur fossils are commonly found in sedimentary rocks with sediment that indicates the environment had___________ at the time the dinosaur was buried.

a river flowing through it.

The rounding of sediment grains can help determine:

a rough idea of the distance that grain has traveled from its original source rock.

As sediment is carried down river, the grains being transported:

become progressively smaller as they are ground down.

Fossilization typically involves which of the following processes?

burial and some form of mineralization

Which type of boundary is illustrated in Figure A below

convergent plate boundary

In the middle Jurassic, the much of the western part of North America was:

covered with vast inland sea.

Carbonization is a type of fossilization that:

creates a 2D film of residue where an organic object used to be.

New oceanic crust is added at _______ boundaries, and old crust is subducted and recycled at _______ boundaries.

divergent, convergent

Fossils are most commonly preserved in areas that had ____ at the time of the organisms' death.

high rates of sedimentation, like a river.

The minerals that replace organic content in buried bones come from:

minerals dissolved in groundwater precipitating (crystallizing) in/on the bones.

Which fossil type involves a process that that slowly fills microscopic voids and replaces organic material at the cellular level to preserve fine internal structure?

permineralization / petrification

The absolute age of a rock unit can be determined by

radiometric dating.

The reason that the very largest organisms like titanosaurs are found as highly incomplete skeletons is because:

rapid burial with sediment is difficult for very large objects.

When the Geologic time scale was being developed, which method of assigning ages to rock units was used first - relative dating or absolute dating?

relative

The principle of biostratigraphic correlation states that _____.

rocks with the same fossils of the same species are the same age.

Fossils are almost always found in which type of rock?

sedimentary

The study of the age relationships between rock units is called:

stratigraphy

The colors on a geologic map represent:

the age of the rocks

A "Depositional environment" is best described as

the ancient environment that existed at the time loose sediment was deposited.

The process of lithification is:

the compaction and cementation of sediment to make a rock.

In the Taphonomy lecture, the focus is on a place in Canada called Dinosaurs Provincial Park. It is a great place to find fossils, but why isn't it a good place for new fossils to form?

the modern environment is dry and barren, so there is little sediment that could bury something that died.

At plate boundaries where continental crust and ocean crust are running into each other, the oceanic crust will be subducted beneath the continental crust because oceanic crust is ___________ than continental crust.

thinner but more dense

Which type of plate boundary does not have a way to bring magma/lava to the Earth's surface?

transform

The grains of sediment that form a sedimentary rock can tell us a lot about what kind of environment the rock formed in. For example, well rounded and well sorted sediments indicates that the sediment:

traveled a long way from its source area.

In the diagram above, the lines marked S, R and P represent

unconformities: missing rock that indicates a period of erosion

The presence of grains of water-soluble minerals in a sedimentary rock indicates the environment in which that rock formed was most likely:

very dry.

Taphonomy is the study of:

what happens to the remains of organisms from death to burial in sediment.

In the image below, the fault marked "H" is (older/younger) than the rock unit marked "E"

younger