Question

Difficulty: MediumAligning Data and Predictions with Viewpoints

Two scientists debate the formation of the Grand Canyon.

Scientist 1
The Grand Canyon was carved slowly over approximately 6 million years. The Colorado River gradually eroded the uplifting Colorado Plateau. The erosion rate remained relatively constant, averaging about 0.15 mm/yr0.15\text{ mm/yr}. This slow process allowed the river to gradually cut through the rising rock strata, depositing fine, well-sorted sediments downstream at a steady rate.

Scientist 2
The Grand Canyon was formed rapidly, likely within a few weeks, by a catastrophic outburst flood. Approximately 5.5 million years ago, a massive prehistoric lake located on the Colorado Plateau breached its natural barrier. The sudden release of water created a massive, high-velocity flow that carved the canyon. This flood would have deposited a thick layer of unsorted gravel and large boulders downstream.

Based on the presented viewpoints, the discovery of a downstream sediment layer containing large, poorly sorted boulders dated to 5.5 million years ago is consistent with the predictions of Scientist 1.

Answer: Answer

Answer

False

Step-by-Step Solution

1
Analyze Scientist 1's predictions regarding downstream sediments.
Scientist 1 predicts that slow erosion deposits fine, well-sorted sediments downstream at a steady rate.
To establish the expected sedimentary evidence for the gradual incision hypothesis.
2
Analyze Scientist 2's predictions regarding downstream sediments.
Scientist 2 predicts that a catastrophic outburst flood would deposit a thick layer of unsorted gravel and large boulders downstream.
To establish the expected sedimentary evidence for the breached lake hypothesis.
3
Compare the new observation of large, poorly sorted boulders dated to 5.5 million years ago with both predictions.
The observation of large, poorly sorted boulders aligns with the high-velocity transport predicted by Scientist 2 and contradicts the slow, steady sedimentation predicted by Scientist 1. Therefore, the statement is false.
To determine the truth value of the proposed statement based on the viewpoints.

Key Concept

Aligning physical geological evidence with predictions derived from competing scientific hypotheses.
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