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| Title |
High Plains Depressions in Eastern Colorado: Distribution, Classification, and Genesis
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| Author(s) |
Walker, Graham Thomas
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| School/Department |
Department of Geography
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| Institution |
University of Denver
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| Degree Type |
Doctoral
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| Degree Name |
Ph.D.
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| Type of Resource |
text
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| Degree Date |
1985 June
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| Digital Origin |
reformatted digital
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| Rights Statement |
All Rights Reserved
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| Reason for Restrictions |
No restrictions
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| Type of Restriction |
No restrictions
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| Keyword(s) |
Geography
Geology
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| Genre |
Dissertations, Academic
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| Abstract |
Closed topographic depressions are widespread across the Colorado Plains with maximum densities in areas of fixed Quaternary sand dunes. A purposive sample of 548 depressions selected from maps of the 1° x 2° and 7.5-minute topographic series was described by five variables measuring the bipolar attributes elongate-circular, compact-irregular, shallow-deep, small-large, and simple-complex. Submission of the resulting data matrix to a hierarchical clustering algorithm discriminated the main genetic classes already identified subjectively, although with some misallocation. The analysis gave no new genetic insights and split some natural groupings that span a morphological continuum but share a common genesis. These limitations reflect deficiencies in specifying the morphological diversity of the sample as well as the mechanical nature of numerical classification procedures. Most sample depressions are primary or secondary eolian forms, ranging from small, regular depositional hollows on sand and loess, through deeper, more elongate blowouts, to large and highly irregular features comprising coalescent interdune flats and corridors. The largest features are found across early Pleistocene pediments undergoing dissection by north-bank tributaries of the South Platte and Arkansas Rivers and preserved by beheading of the pediment drainage. They result from solution-subsidence associated with Permian evaporites and from eolian disruption of broad shallow valleys comprising the original pediment drainage. Smaller stellate forms in central Washington County result from disruption of the incised High Plains drainage by loess drifts.
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| Handle |
http://hdl.handle.net/10176/codu:57845
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| Attached Files |
| Name |
Description |
MIMEType |
Size |
Downloads |
du_mas_1985_Walker.pdf
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du_mas_1985_Walker.pdf |
application/pdf |
7.04MB |
0 |
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