Layers of volcanic ash often serve as useful geologic time markers because ash layers usually

Letters A through D represent landscape features, and numbers 1 through 7 represent rock layers. The detail shows a fossil found in layer 3. What is the correct sequence of events from oldest to most recent in the geologic history of this area?

Overturning has not occurred, the dike and sills shown in the cross section are igneous rock intrusions. Which rock type is the oldest?

The diagram shows a geologic cross section. Letters A through D represent different rock units. Which sequence correctly shows the age of the lettered rock units, from oldest to youngest?

In the geologic cross section, overturning has not occurred. Letters A through H represent rock layers. Which two letters represent bedrock of the same age?

The cross section represents four different rock units. The symbol for contact metamorphism has been omitted from the cross section. Which cross section below represents where the symbol for contact metamorphism would be located, based on the relative age sequence?

The sequence of rock types found in the walls of the Grand Canyon are shown. The names of rock formations are shown and the upper and lower boundaries of each formation are indicated by dashed lines. The rock layers have not been overturned. The sequence of rock layers in the cross section provides evidence that the Muave formation is

The geologic cross section of the Grand Canyon shows numbers 1-10 that represent Paleozoic sedimentary rock layers. The unconformity between the Paleozoic sedimentary rocks and the Precambrian sedimentary rocks represents

The three geologic columns represent the rock layers in outcrops located several miles apart. The rock layers have not been overturned. Two different index fossils are shown. Of the rock layers found in these three outcrops, which layer was probably formed most recently?

An igneous rock contains 10 grams of radioactive potassium-40 and a total of 10 g of its decay products. During which geologic time interval was this rock most likely formed?

What is the geologic age sequence of the surface bedrock from Ithaca, NY to Watertown, NY?

A fossil formed 11,400 years ago. Which percentage of the original amount of carbon-14 remains in the fossil?

The graph below shows the decay of a radioactive material over time. How long does it take for this radioactive material to decay through 2 half lives?

Which radioactive isotope is most often used when determining the age of fossil bones found in sediments deposited during the Holocene Epoch?

Due to radioactive decay, an igneous rock sample now contains 1/4 of the amount of potassium-40 that it originally contained. The age, in years, of this rock sample is approximately

The table shows how the radioactive decay of potassium-40 can be used to determine the age of a rock. How old is a sample of granite that contains 8 grams of radioactive potassium-40 and 56 grams of its nonradioactive decay products?

The diagram represents a sample of rubidium-87 (⁸⁷Rb). Which diagram represents the correct proportion of ⁸⁷Rb to its decay product, ⁸⁷Sr, after two half-lives?

This index fossil was found in surface bedrock in NYS. Index fossils, such as the one in the diagram, are useful to geologists for correlating rocks because each species

THe diagrams below represent the rock layers and fossils found at four widely separated rock outcrops. Which fossil appears to be the best index fossil?

Which pie graph best shows the relative length of time of the major intervals of Earth's geologic history?

The diagram shows specific events in the history of Earth from the beginning of the universe to the present. During which geologic era did life first appear on land?

Which major mountain-building episode is most recent?

According to the Geologic History of NYS chart in the ESRT, the inferred latitude of NYS 362 million years ago was closest to

Valcouroceras is a NYS index fossil. Which mountain-building event occurred in NYS during the time when Valcouroceras was living in oceans covering parts of NYS?

What is the age of most of the surface bedrock found in NYS at a latitude of 45^o?

NYS has no bedrock from which geologic time period?

What is the geologic age of the surface bedrock of most of the Allegheny Plateau landscape region in NYS?

The largest meteorite impact crater in North America formed approximately 1,850 million years ago, which was during the

Which sequence shows the correct order of Earth's geologic time intervals from oldest to youngest?

Which two types of organisms both survived the mass extinction that occurred at the end of the Permian period?

The major source of oxygen in Earth's Early Proterozoic atmosphere is inferred to have been produced by

Which statement about the species of animals and plants that lived on Earth in the past is best supported by the fossil record?

Which life-form existed on Earth during the same time period?

The diagram shows the evolutionary development of the horse, as supported by the fossil record. Which statement best explains the changing appearance of the horse, as supported by the fossil record?