Earth's History Assessment

During which geologic epoch do scientists infer that the earliest grasses first appeared on Earth?

• Oligocene

• Holocene

• Eocene

• Pleistocene

An igneous intrusion was examined and scientists found that this rock had about 25% of the overall uranium-238 left in the composition of the rock. Using the amount of uranium-238 left in the intrusion, how old is the intrusion?

• 4.5 billion years

• 9.0 billion years

• 13.5 billion years

• 18 billion years

The photograph shows a small waterfall located on the Tug Hill Plateau.

During which geologic time period was the surface bedrock at this location formed?

• Triassic

• Ordovician

• Devonian

• Cretaceous

Radioactive dating of fossils and rocks is possible because radioactive isotopes

• disintegrate at a predictable rate

• are easily collected and measured

• are found in all fossils and rocks

• disintegrate into organic substances

The cross sections represent two rock outcrops, labeled I and II, located 10 miles apart. Letters A through E and numbers 1 through 8 identify rock units. The rock units have not been overturned.

The rock record in outcrop II suggests that an unconformity probably exists in outcrop I between rock units

• B and C

• C and D

• D and E

• A and B

The map shows the current location of New York State in North America.

Approximately how many million years ago (mya) was this New York State region located at the equator?

• 458 mya

• 359 mya

• 119 mya

• 59 mya

Which mountains were formed during the late Carboniferous (Pennsylvanian)?

• Appalachian (Allegheny) Mountains

• Catskill Mountains

• Adirondack Mountains

• Taconic Mountains

The photograph shows a New York State index fossil.

What is the best classification of this fossil, and during which geologic time period did the organism that produced this fossil exist?

• Classification: Trilobite

  Geologic time period: Ordovician

• Classification: Trilobite

  Geologic time period: Permian

• Classification: Coral

  Geologic time period: Ordovician

• Classification: Coral

  Geologic time period: Permian

During the late Silurian epoch, very salty seas extended from New York State to Michigan. These environmental conditions resulted in the formation of halite layers. At the same time, Eurypterus remipes lived in nearby environments. Both the halite layers and Eurypterus remipes fossils can now be used to identify a specific geologic time interval because both formed over a

• large geographic area and in a short geologic time

• small geographic area and in a long geologic time

• small geographic area and in a short geologic time

• large geographic area and in a long geologic time

The outcrops, labeled I, II, and III, are located within 15 kilometers of each other. Lines AB and CD represent unconformities. Line XY represents a fault. No overturning of the layers has occurred.

The unconformities at AB and CD resulted from

• movement along a crack between two rock layers

• regional metamorphism of deeply buried sedimentary rocks

• uplift and erosion, followed by subsidence and deposition

• contact metamorphism between two sedimentary layer