Exam 11: Geologic Time

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 are true?

What general term denotes a buried, erosional surface where rock layers are missing?

What process involves identifying and matching rocks of similar ages in different areas?

The ________ is the idea or concept that ancient life forms succeeded each other in a definite, evolutionary pattern and that the contained assemblage of fossils can determine geologic ages of strata?

Word Analysis. Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.

(a) In the chart of radioactive decay shown below, how many half-lives have elapsed by time (a)?_______________ (b) How many half-lives have elapsed by time (b)? _______________

For a radioactive isotope like Uranium-235, what does the 235 indicate?

What kind of unconformity is produced when tilted, older strata are eroded and buried by younger strata?

The geologic time scale was devised before numerical dating using radioactivity was invented.

Phanerozoic, marine, sedimentary strata of the same age on different continents can usually be correlated by their fossil assemblages.

In an undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below. The preceding is a statement of the law of ________.

An unconformity is a buried ________.

You are asked to interpret the geologic history of a county in California where the geology is quite complex. Aside from visiting various sites in the county for observing geologic sites firsthand, you are permitted to request five different pieces of information or data to aid in your interpretation. List the five that you would choose and explain why each is important for your study.

Examine the geologic cross section below. (a) Which feature is the youngest? ______________________________ (b) Which feature is the oldest? ______________________________

Most sedimentary rocks are readily dated by radiometric methods.

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

The era known as the "age of mammals" is the ________.

On the blank provided beside each geologic cross section below, write the name of the specific type of unconformity that is labeled with an arrow. The v-pattern indicates igneous rocks. All other patterns are different types of sedimentary rocks. (a) ______________________________ (b) ______________________________ (c) ______________________________

Pebbles of granite in sandstone and conglomerate resting on the granite suggest that the granite intruded the sedimentary beds.

All of geologic time prior to the beginning of the Paleozoic era is termed the Phanerozoic eon.