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The geologic record is in no one place entirely complete [1] for where geologic forces one age provide a low-lying region accumulating deposits much like a layer cake, in the next may have uplifted the region, and the same area is instead one that is weathering and being torn down by chemistry, wind, temperature, and water.
The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is called a hiatus. It is a kind of relative dating.
A gap is a geological formation that is a low point or opening between hills or mountains or in a ridge or mountain range. It may be called a col, notch, pass, saddle, water gap, or wind gap. Geomorphologically, a gap is most often carved by water erosion from a freshet, stream or a river. [1]
Geologic stratigraphic column of strata exposed in and near the Grand Canyon. The term Great Unconformity is frequently applied to the unconformity observed by John Wesley Powell in the Grand Canyon in 1869. [1] It is an exceptional example of relatively young sedimentary rock strata overlying much older sedimentary or crystalline strata.
Unconformities are gaps in the geologic record within a stratigraphic unit. These gaps can be caused by periods of non-deposition or by erosion. [3] As a result, two adjacent rock units may have significantly different ages.
Unconformities are particularly important in understanding geologic history because they represent erosional surfaces where there is a clear gap in the record. Conversely within a sequence the geologic record should be relatively continuous and complete record that is genetically related. [1] [2] [3] [4]
Pages in category "Gaps in the fossil record" The following 7 pages are in this category, out of 7 total. This list may not reflect recent changes. A. Arthropod gap; C.
First considered to be a preservational gap in the fossil record, the event was originally dubbed 'Olson's Gap'. [ 4 ] [ 10 ] To compound the difficulty in identifying the cause of the 'gap', researchers were having difficulty in resolving the uncertainty which exists regarding the duration of the overall extinction and about the timing and ...