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Jacky_Ye
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username2088165
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(Original post by Jacky_Ye)
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Please help me with my Geography h/w. The task is to write how A, B and C are formed and a geological history about them. Thanks
B - the rocks here aren't folded, however they have been eroded. Again, write about the order in which the rocks were deposited, and how erosion has affected them.
C - in this cross section, the concept of 'cross-cutting relationships' is an important tool to use to figure out what's going on. Structures such as faults and igneous intrusions 'cross-cut' the rocks which are already there, so are therefore younger than the rocks they cut through. The oldest rock is the clay, followed by the sandstone and limestone, which lie in horizontal beds. A fault has displaced these beds upwards, and the basalt intrusion has intruded into them. Both the fault and the intrusion stop at the sandstone, meaning that a period of erosion must have occurred, followed by the deposition of the sandstone.
I hope that helps
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Jacky_Ye
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#3
(Original post by Leviathan1741)
A - all sedimentary layers are deposited more or less horizontally, so here you should list the order in which the rock types were deposited, then describe the process which caused them to deform (i.e. fold).
B - the rocks here aren't folded, however they have been eroded. Again, write about the order in which the rocks were deposited, and how erosion has affected them.
C - in this cross section, the concept of 'cross-cutting relationships' is an important tool to use to figure out what's going on. Structures such as faults and igneous intrusions 'cross-cut' the rocks which are already there, so are therefore younger than the rocks they cut through. The oldest rock is the clay, followed by the sandstone and limestone, which lie in horizontal beds. A fault has displaced these beds upwards, and the basalt intrusion has intruded into them. Both the fault and the intrusion stop at the sandstone, meaning that a period of erosion must have occurred, followed by the deposition of the sandstone.
I hope that helps
A - all sedimentary layers are deposited more or less horizontally, so here you should list the order in which the rock types were deposited, then describe the process which caused them to deform (i.e. fold).
B - the rocks here aren't folded, however they have been eroded. Again, write about the order in which the rocks were deposited, and how erosion has affected them.
C - in this cross section, the concept of 'cross-cutting relationships' is an important tool to use to figure out what's going on. Structures such as faults and igneous intrusions 'cross-cut' the rocks which are already there, so are therefore younger than the rocks they cut through. The oldest rock is the clay, followed by the sandstone and limestone, which lie in horizontal beds. A fault has displaced these beds upwards, and the basalt intrusion has intruded into them. Both the fault and the intrusion stop at the sandstone, meaning that a period of erosion must have occurred, followed by the deposition of the sandstone.
I hope that helps
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Jacky_Ye
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#4
(Original post by Jacky_Ye)
Alright, thanks!
Alright, thanks!
(Original post by Leviathan1741)
A - all sedimentary layers are deposited more or less horizontally, so here you should list the order in which the rock types were deposited, then describe the process which caused them to deform (i.e. fold).
B - the rocks here aren't folded, however they have been eroded. Again, write about the order in which the rocks were deposited, and how erosion has affected them.
C - in this cross section, the concept of 'cross-cutting relationships' is an important tool to use to figure out what's going on. Structures such as faults and igneous intrusions 'cross-cut' the rocks which are already there, so are therefore younger than the rocks they cut through. The oldest rock is the clay, followed by the sandstone and limestone, which lie in horizontal beds. A fault has displaced these beds upwards, and the basalt intrusion has intruded into them. Both the fault and the intrusion stop at the sandstone, meaning that a period of erosion must have occurred, followed by the deposition of the sandstone.
I hope that helps
A - all sedimentary layers are deposited more or less horizontally, so here you should list the order in which the rock types were deposited, then describe the process which caused them to deform (i.e. fold).
B - the rocks here aren't folded, however they have been eroded. Again, write about the order in which the rocks were deposited, and how erosion has affected them.
C - in this cross section, the concept of 'cross-cutting relationships' is an important tool to use to figure out what's going on. Structures such as faults and igneous intrusions 'cross-cut' the rocks which are already there, so are therefore younger than the rocks they cut through. The oldest rock is the clay, followed by the sandstone and limestone, which lie in horizontal beds. A fault has displaced these beds upwards, and the basalt intrusion has intruded into them. Both the fault and the intrusion stop at the sandstone, meaning that a period of erosion must have occurred, followed by the deposition of the sandstone.
I hope that helps
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username2088165
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#5
(Original post by Jacky_Ye)
Hey Levi! Please can you do part A for me as an example because I really don’t get it :/ Thank you
Hey Levi! Please can you do part A for me as an example because I really don’t get it :/ Thank you
Point 1 says that rocks get younger from the bottom up, which just means that the rocks at the bottom are the oldest, and the rocks at the top are the youngest. In this case, the sandstone is the oldest rock, the limestone is younger, and the clay is the youngest rock type. Point 2 tells you that layers can be assumed to have been originally horizontal, and the rocks in the image are wavy, not horizontal, meaning they have been folded.
In summary, the sandstone, then limestone, then clay were deposited horizontally, and later they were folded
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Jacky_Ye
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#6
(Original post by Leviathan1741)
Okay, I'll just go through A
Point 1 says that rocks get younger from the bottom up, which just means that the rocks at the bottom are the oldest, and the rocks at the top are the youngest. In this case, the sandstone is the oldest rock, the limestone is younger, and the clay is the youngest rock type. Point 2 tells you that layers can be assumed to have been originally horizontal, and the rocks in the image are wavy, not horizontal, meaning they have been folded.
In summary, the sandstone, then limestone, then clay were deposited horizontally, and later they were folded
Okay, I'll just go through A
Point 1 says that rocks get younger from the bottom up, which just means that the rocks at the bottom are the oldest, and the rocks at the top are the youngest. In this case, the sandstone is the oldest rock, the limestone is younger, and the clay is the youngest rock type. Point 2 tells you that layers can be assumed to have been originally horizontal, and the rocks in the image are wavy, not horizontal, meaning they have been folded.
In summary, the sandstone, then limestone, then clay were deposited horizontally, and later they were folded
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username2088165
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Jacky_Ye
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#9
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#9
For B, the rocks haven't been folded, and I can't see any faults on there. I would say that the sandstone, limestone and clay were deposited horizontally, then eroded (you can see that there are gaps in the the clay, and some of the limestone is missing where it has been removed by erosion).
C is a bit trickier. Remember to always start with the deposition of the rocks - clay, sandstone, and then limestone. The three rocks have been faulted and moved upwards, and the basalt has intruded into them. The rocks, including the basalt, were then eroded (shown by the wavy, smooth surface), and lastly, sandstone was deposited on top of everything.
Does that make sense? I do geology as my degree, and I know these can be hard to understand at first
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