a
F
F
F
A
A
T
T
T
T
T
T
T
H
H
H
Unconsolidated
gravel, sand, and silt
Gneiss and
igneous rock of
Precambrian age
from E. J. Crosby
, 1978
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Notes:
This three-dimensional perspective of the project
demonstration area shows the physiographic setting of Urban Corridor gravel
deposits:
1-All of the gravel deposits of the Front Range Urban Corridor can be classified into one of four types according to physiographic setting (landforms): 1) piedmont alluvial fans, 2) high dissected terraces, 3) terraces, and 4) floodplains and low terraces. The first three types are Pleistocene in age; they have been eroded to varying degrees.
2-Piedmont alluvial fans are coarse, poorly sorted deposits at the foot of the mountains.
3-High dissected terraces are the downstream continuation of alluvial fan surfaces. Commonly, they are erosional remnants of surfaces that were once more extensive.
4-Stream terraces are more or less continuous and occur at a distinctly higher level than the floodplain, but below the level of high dissected terraces.
5-Floodplain and low terrace deposits of Holocene age are currently the major source of gravel in the Urban Corridor.
6-The four deposit types are the basis for definition of gravel deposit models. Because of their importance, project investigations of deposit models to date have concentrated entirely on floodplain deposits.
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Last updated 07 Dec 2016