This is a form, with questions. It is the equivalent of three pages. It answers a series of questions related to the geologic history of the Grand Canyon. Covered are issues related to the Layered Paleozoic Rocks, Grand Canyon supergroup Rocks, and Vishnu Basement Rocks. There is also a section for the identification of rock samples, using a website that tells you the hardness and other characteristics.
Geology
Identify each of the events represented on diagram 1. Include at least the information below:
(1) Begin with the oldest event. Make sure that you somehow tell me which event is the oldest, which is the next oldest, etc.
The oldest lettered event in the diagram is (C), referring to the sedimentary layer of limestone. The next oldest event is (B), which is the basalt and silt layer that infiltrated. The next oldest event is (A), which shows the impingement of the Colorado River. The youngest of these four lettered events is (D), which is a fault event and might represent the Great Unconformity.
(2) Name of feature or rock represented by each given symbol. Don't forget to include the faults, which are represented by A, C, and D.
(A) represents an inner gorge, which might have occurred due to the impact and subsequent erosion of magma
(B) is a diabase layer, consisting of dikes and sills, which were deposited via the ocean.
(C) is the sedimentary layer of limestone. Although most limestone in the Grand Canyon is not of the oldest era, the letters in the diagram do not cover the older layers such as the Vishnu Schist.
(D) represents the Great Unconformity
(3) Describe the ancient event or process that caused the feature or rock to be made. By "event" or "process, I mean processes like sea level rising or falling, igneous activity due to convergence, igneous activity due to divergence, magma intrusion, etc.
(A) Above the most basic layer of the Grand Canyon, consisting of the metamorphic rock basin, is a level of the inner gorge. Magma rose and cooled, and these originally lava layers were then removed by subsequent erosions. This has left the lower gorge formations and gaps.
(B). The diabase layer was formed by sandstone, shale, and other deposits during the Paleozoic Era.
(C) This layer of limestone was then deposited, and pushed upwards by:
(D), Which represents the pressing up and down of the Supergroup rocks, and the Great Unconformity in which there are some gaps in geological history.
C. Answer these questions about dating techniques and event ages:
(1) Describe how the radiometric dating techniques can be used to measure the absolute numerical age of the youngest rock on this diagram.
Radiometric dating offers a reliable method of measuring the absolute numerical age of the youngest rock, by measuring the decay rates relative to radioactive isotopes.
(2) What principles of stratigraphy could we use to measure the relative age of the youngest rock on this diagram? Give at least two (2) principles.
Several principles of stratigraphy can be used to measure the relative age of the youngest rock in the diagram. The most apparent include lithologic, which would measure the age based on the surrounding layers and their placement: showing the sequence in which each layer was formed. However, this layer is young enough that it would be beneficial to use biostratiagraphy because of the possible presence of biological material like fossils. Also, chronostratiagraphy can be used to propose an exact time for this layer based on the rock composition.
(3) What type of dating technique should be used to give a numerical date the largest igneous intrusion in this diagram?
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