QUESTION: 597 Topic Exam C: Section 3 (science)

Sedimentary rocks (which form from sediment) are thought to be deposited in cycles that occur in discrete packages called sequences. Each sequence constitutes a complete cycle. The cause for the cyclist has been linked to sea level change, uplift of continents, climate change, and changes in earth's orbit. These packages are thought to have a duration ranging from 50,000 to 200 million years.

One theory states that the sequences that occur on a scale of every 200,000 to 10 million years are usually caused by changes in the global ice volume. As temperatures increase and glaciers melt, sea level rises and new marine sediment which is typically coarser-grained than underlying sediments is deposited along shorelines. As global temperatures decrease and glaciers build up, sea level falls and shoreline environments are eroded.

In order to test this theory, two studies were undertaken which enable us better to understand the relations between glaciations (periods of maximum cooling and glacier build-up) and marine sedimentary sequences.

Study 1
A 400m long core of sedimentary rock from an ancient shoreline in the United States was analyzed. The core represents marine sediments deposited over the last 20 million years. The researchers observed patterns of erosion and change in sediment size and determined that unique sequences occurred every 50,000, 100,000, 5 million, and 12 million years.

Study 2
At several sites beneath the Atlantic Ocean, a 50m core was removed from 500,000-year-old ocean floor marine sediments. These sediments contained abundant microfossils that can be used in determining the nature of past climates. The researchers studied the abundance and taxonomy of these microfossils and deduced patterns of warming and cooling global temperatures. They found that periods of maximum cooling (peak glaciations) occurred 75,000, 175,000, 375,000, and 475,000 years ago.

The characteristics common to the studies is that both:

measured periods of maximum glaciations.
utilized ancient and modern sedimentary rocks.
analyzed data from marine sediments.
measured the depth of the cycles.

Answer(s): C

Explanation:

Both studies state that they are analyzing marine sediment. Study 2 makes no mention of sedimentary rocks (ruling out choice B). Depth of the cores is irrelevant (ruling out choice D) and only Study 2 states that it measured peak glaciations (ruling out choice A).

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QUESTION: 598 Topic Exam C: Section 3 (science)

Sedimentary rocks (which form from sediment) are thought to be deposited in cycles that occur in discrete packages called sequences. Each sequence constitutes a complete cycle. The cause for the cyclist has been linked to sea level change, uplift of continents, climate change, and changes in earth's orbit. These packages are thought to have a duration ranging from 50,000 to 200 million years.

One theory states that the sequences that occur on a scale of every 200,000 to 10 million years are usually caused by changes in the global ice volume. As temperatures increase and glaciers melt, sea level rises and new marine sediment which is typically coarser-grained than underlying sediments is deposited along shorelines. As global temperatures decrease and glaciers build up, sea level falls and shoreline environments are eroded.

In order to test this theory, two studies were undertaken which enable us better to understand the relations between glaciations (periods of maximum cooling and glacier build-up) and marine sedimentary sequences.

Study 1
A 400m long core of sedimentary rock from an ancient shoreline in the United States was analyzed. The core represents marine sediments deposited over the last 20 million years. The researchers observed patterns of erosion and change in sediment size and determined that unique sequences occurred every 50,000, 100,000, 5 million, and 12 million years.

Study 2
At several sites beneath the Atlantic Ocean, a 50m core was removed from 500,000-year-old ocean floor marine sediments. These sediments contained abundant microfossils that can be used in determining the nature of past climates. The researchers studied the abundance and taxonomy of these microfossils and deduced patterns of warming and cooling global temperatures. They found that periods of maximum cooling (peak glaciations) occurred 75,000, 175,000, 375,000, and 475,000 years ago.

The two studies support the theory that marine depositional processes are:

controlled by microfossils and local climate changes.
unpredictable in nature.
most likely controlled by the cycling of glacial building and melting.
related to sequences of marine sediments.

Answer(s): C

Explanation:

Choices C and D are tough, but if the student compares the numbers from Study 1 and 2, he or she will see that 100,000 years is a common factor to both studies, so choice C is the most accurate answer. Choice D is too vague, and ignores the results of Study 2. There is no indication that region and microfossils control marine depositional processes (ruling out choice A). Both studies show that there are patterns in these processes, making choice B a poor selection.

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QUESTION: 599 Topic Exam C: Section 3 (science)

Sedimentary rocks (which form from sediment) are thought to be deposited in cycles that occur in discrete packages called sequences. Each sequence constitutes a complete cycle. The cause for the cyclist has been linked to sea level change, uplift of continents, climate change, and changes in earth's orbit. These packages are thought to have a duration ranging from 50,000 to 200 million years.

One theory states that the sequences that occur on a scale of every 200,000 to 10 million years are usually caused by changes in the global ice volume. As temperatures increase and glaciers melt, sea level rises and new marine sediment which is typically coarser-grained than underlying sediments is deposited along shorelines. As global temperatures decrease and glaciers build up, sea level falls and shoreline environments are eroded.

In order to test this theory, two studies were undertaken which enable us better to understand the relations between glaciations (periods of maximum cooling and glacier build-up) and marine sedimentary sequences.

Study 1
A 400m long core of sedimentary rock from an ancient shoreline in the United States was analyzed. The core represents marine sediments deposited over the last 20 million years. The researchers observed patterns of erosion and change in sediment size and determined that unique sequences occurred every 50,000, 100,000, 5 million, and 12 million years.

Study 2
At several sites beneath the Atlantic Ocean, a 50m core was removed from 500,000-year-old ocean floor marine sediments. These sediments contained abundant microfossils that can be used in determining the nature of past climates. The researchers studied the abundance and taxonomy of these microfossils and deduced patterns of warming and cooling global temperatures. They found that periods of maximum cooling (peak glaciations) occurred 75,000, 175,000, 375,000, and 475,000 years ago.

Which of the following characteristics of a sequence of marine sediments or sedimentary rocks would make it unsuitable for a study such as this?

I). an age of only 30,000 to 40,000 years
II). depth of ocean water
III). location away from the polar ice caps

I only
II and II only
I, II, and III
I and III only

Answer(s): A

Explanation:

The passage makes no mention of the relevance of ocean depth or proximity to polar ice caps, but it does mention that these sequences have a minimum age of 50,000 years.

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QUESTION: 600 Topic Exam C: Section 3 (science)

Both studies are compatible with the claim that major climate changes occur at intervals of 50,000 years or more.
Both studies provide support for the claim that cyclic climate changes caused changes in sediment patterns.
Sediment size was a central factor in the results of both studies.
Both studies concerned ancient marine sedimentary rocks.

Answer(s): C

Explanation:

Sediment size was the crucial factor in Study 1, but not Study 2 (where the central factors were the abundance and shape of microfossils).

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