Question

The photograph below shows a roadcut, a human-made outcrop (rock exposure) alongside the highway. The gray layers are shale and the tan layers are sandstone. The students studying this outcrop made the following observations: 1. Fossils of marine invertebrates occur in the dark shale at the base of the outcrop. 2. Fossils of plants that grow in swamps occur in the sandstone near the top. 3. The lowermost sandstone layer fills a channel cut down into the shale below. Which of the following are reasonable interpretations of depositional environments of the sediments from which these rocks formed?there are two correct answers The sandstone was deposited near the coast. The shale was deposited on a floodplain. The shale was deposited in a lake. The sandstone was deposited in a mountainous, rocky environment. The sandstone was deposited in an inland desert. The shale was deposited in the ocean.

Answer 1

The reasonable interpretations of the depositional environments of the sediments from which these rocks formed are: the sandstone was deposited near the coast, and the shale was deposited on a floodplain.

Step-by-step explanation:

The reasonable interpretations of the depositional environments of the sediments from which these rocks formed are:

• The sandstone was deposited near the coast. The presence of fossils of plants that grow in swamps in the sandstone near the top suggests a coastal environment where swamps are located.
• The shale was deposited on a floodplain. The presence of fossils of marine invertebrates occurring in the dark shale at the base of the outcrop indicates that the shale was deposited in an area influenced by a freshwater environment, such as a floodplain.

Answer 2

The observations indicate that the dark shale was deposited in a marine environment, likely the ocean, while the tan sandstone with swamp plant fossils was deposited near the coast.

Step-by-step explanation:

Based on the observations made from the roadcut, two reasonable interpretations for the depositional environments where the sediments were deposited can be deduced. First, the presence of marine invertebrate fossils in the dark shale at the base suggests that the shale was deposited in a marine environment, which is typically characterized by low oxygen conditions, supporting the presence of these types of fossils. Hence, it is likely that the shale was deposited in the ocean. The second correct interpretation pertains to the tan sandstone layers containing swamp plant fossils, which align with a coastal swamp environment. Considering the data on the location of the deposition of various sediments, we can conclude that the sandstone was likely deposited near the coast, as sand is known to be deposited close to shore in coastal environments. Therefore, the correct interpretations are:

• The sandstone was deposited near the coast.
• The shale was deposited in the ocean.