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Formation of an Unconformity:
An Unconformity may develop due to the changes in the process of deposition due to which there is a break in the deposition. This may also take place due to Upheaval of the deposition surface (or basin). Such upheavals consequently lead to erosion and/or deformation of the uplifted rock strata on account of its exposure to the active deforming geological agents such as water, wind, glaciers, etc.
Upon the upper surface of the pre-existing strata which was being uplifted (and which may or may not have undergone any deformation), a second set of mutually Conformable rock beds may be deposited during the geological periods of fresh sedimentation cycles. This may also take place due to Submergence of the Uplifted Strata followed by the deposition of the younger rock beds.
The two formation which then lie in contact with each other are actually Unconformably related to each other. And thus the resulting structure is termed as an Unconformity.
The time period of no deposition or erosion is called as "Hiatus."
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Steve
BlakeTwo ways unconformities form when...
1) When deposition stops after a supply of sediment is cut off.
2) When erosion removes layers in sedimentary rock.
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That needs amplifying. An unconformity results when new rock is deposited on existing rock, with the expected intervening sequence either not deposited in the first place (as point 1 above hints at) or eroded away as (point2) says, though the older rock need not be sedimentary. If the unconformity's basement dips at a different angle to the new rocks, as is common, the unconformity is described as "angular".
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How do geologist know he or she is looking at a disconformity?
Geologists can identify a disconformity by observing a gap in the rock record where there is evidence of erosion or non-deposition between parallel rock layers. The key characteristic is that the rock layers above and below the disconformity are parallel, indicating a period of missing time in the geological record.
What is disconformity?
A disconformity is a type of unconformity in geology where the rock layers are parallel, but there is a significant age gap between them due to erosion or non-deposition. This can create a discontinuity in the rock record.
Illustrate a disconformity?
A disconformity is a type of unconformity where there is an age gap between horizontally parallel layers of rock. This means that there is missing rock record between the layers, indicating a period of erosion or non-deposition. It is often harder to visually identify disconformities compared to other types of unconformities like angular unconformities.
How can you tell when your looking at a disconformity?
A disconformity is identified by a break in the rock record where the layers above and below are parallel, indicating a period of erosion or non-deposition. It may show different erosional patterns or changes in the rock type, texture, or fossils between the two layers. Time gaps between the two rock units can also suggest a disconformity.
How does a geologist know when he or she is looking at a disconformity?
A geologist identifies a disconformity by observing a gap in rock layers where erosion has removed some layers, creating a visible interruption in the sequence of strata. This gap can be recognized by differences in the type of rock, fossils, or physical features above and below the disconformity. Additionally, the rock layers above and below the disconformity may be parallel, indicating a period of erosion or non-deposition.
