3 SEDIMENTARY FACIES Depositional environments vary from location to location. A
ID: 289623 • Letter: 3
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3 SEDIMENTARY FACIES Depositional environments vary from location to location. A particular place on can also change depositionol environments over time. 1. An area has a layer of sandstone that is interpreted to have once been o edo you of that sandstone is a layer of limestone about the sea level of this area? a beoch. On top that formed deep in the ocean. What can you say Limestone Sandstone 2. Two students are debating about how layers of sondstone and shale (mudstone) relate to rising sea level Student 1: Sondstone forms from sand deposited right at the ocean's edg shale forms from sediments deposited in deeper water. So, if the water was shelo first, and then it got deeper, sandstone would be the first layer deposited so if is o the bottom, and shale would be on top. Student 2: But if the water is getting deepe,that means the shale should be deeper becouse it forms from sediments deposited in deeper water. So, I think er the sand is deposited the mud that will furn into shale would sink under the and form a layer there becouse it forms in deeper water. With which student do you agree? Why? 3. The diagrams on this page show layers of rock. Which rock layer formed first? bottom middle top 4. If rock formed from sediments deposited on the land, what rock could make up the layer? conglomerate limestone sandstone shale (mudstone) coa 5. If rock formed from sediments deposited in deep water, what rock could make up the layer? conglomerate limestone sadstone shale (mudstone) coa the sea level is rising over time. The area started on land and was covered by deeper and 6. In the diagram below, write a series of three rock types that could form in an area where deeper water over time. Explain your sequence. top rock layer: middle rock layer: bottom rock layer: Lecture Tutorials for Introductory Geoscience C W. H. Freeman and Company 81Explanation / Answer
1. Limestone deposits in marine condition so when there is a deposit of limestone over sandstone then there is a rise in sea water (transgression) and thus the rising sea water deposited limestone over the beach sandstone.
2. I agree with the first student. if the ocean was shallow then the sand is deposited at the oceans edge where as whwn the ocean water is rising or getting deeper then the oceans edge will also shift landward and thus shale will start depositing over previously formed sandstone.
3. the rock layers formes sequentialy in an ideal condition (law of superposition)
so bottom rock layer is first formed followed by the middle layer then the top layer.
4. probably sandstone or conglomerate.
5. probably a limestone layer
6.bottom layer- Sandstone (beach)
middle layer- shale (shallow marine)
top layer- limestone (deep marine)
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