2026 EARTH 2nd Semester Final Part 1-AI

Which of the following is most important in interpreting past environments from layers of sedimentary rocks?

• finding rock layers that have not been metamorphosed

• measuring the thickness of each rock layer in a sequence

• type and distribution of fossils are BEST indicator of an area’s ancient conditions & climate

• understanding that younger rock layers are at the bottom of a sequence

Answer explanation

The type and distribution of fossils provide crucial insights into ancient environments and climates, making them the best indicators for interpreting past conditions in sedimentary rock layers.

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Which of the following is an example of a trace fossil?

• bird's footprint

• an intact dinosaur tooth

• a carbonized imprint of a leaf

• a spider in amber

Answer explanation

A bird's footprint is a trace fossil because it provides evidence of the organism's activity, while the other options are body fossils, representing parts of the organism itself.

Living corals are found in warm shallow seas. Coral fossils have been found in the sedimentary rocks of Alaska. These findings suggest that

• ocean currents carried the coral to Alaska

• Alaska once had a tropical marine environment

• coral usually develops in cold climates

• Alaska's cold climate fossilized the coral

Answer explanation

The presence of coral fossils in Alaska indicates that the region once had a warm, tropical marine environment, as living corals thrive in such conditions, not in cold climates.

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NGSS.MS-ESS2-3

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According to Darwin's theory of evolution, differences between species may be the result of

• mutagenic agents

• the transmission of acquired characteristics

• natural selection

• the disuse of body structures

Answer explanation

According to Darwin's theory, natural selection is the process by which species evolve over time. It explains how advantageous traits become more common, leading to differences between species.

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The same geologic processes that occur today were the same process that occurred in the past, and that geologic formations and structures can be interpreted by observing present-day actions.

a. Principal of Uniformitarianism

• Principal of Uniformitarianism

• Law of Original Horizontality

• Law of Superposition

• Cross Cutting Relationships

Answer explanation

The Principal of Uniformitarianism states that the same geological processes observed today have operated in the past, allowing us to interpret geological formations based on current actions.

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The diagram to the right shows a geologic cross section of a region where no faulting has occurred. Which statement about the geologic history of the area is best supported by the evidence in the diagram?

• The rocks at A formed before those at B.

• The rocks at D folded after the deposition of rock layer B.

• A long period of erosion took place before the deposition of rock layer B.

• The major agent of erosion acting on the present surface is ice.

Answer explanation

The diagram indicates that rock layer B was deposited after a significant period of erosion, which is supported by the absence of any layers above it. This suggests that erosion occurred before B's deposition.

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NGSS.MS-ESS1-4

Which layers show folding?

• A and E

• A and B

• E and F

• B and F

Answer explanation

Layers E and F exhibit folding due to their structural characteristics, which indicate deformation. The other options do not show this feature, making E and F the correct choice.

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Faulting occurred after which layer of rock was formed?

• E

• C

• G

• J

Answer explanation

Faulting occurs after the formation of layer C, indicating that the layers above it were disturbed by tectonic activity. Therefore, the correct answer is C.

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You can recognize that this “eye” shaped structure is a dome and not a basin because

• A dome has the youngest rock layers exposed in the center.

• Center of a dome is at a lower elevation than the edges.

• A dome has the oldest rock layers exposed in the center

• A basin has the oldest layers of rock at the center.

Answer explanation

A dome has the oldest rock layers exposed in the center, which distinguishes it from a basin where the oldest layers are also at the center. This characteristic confirms the structure is a dome.

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Ocean currents help regulate Earth’s climate by

• providing energy for hurricanes

• storing and transporting heat

• increasing CO2 levels in the atmosphere

• forming salt deposits to dry out wetlands

Answer explanation

Ocean currents play a crucial role in regulating Earth's climate by storing and transporting heat across the planet, which helps to moderate temperatures and influence weather patterns.

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