Paternoster or Staircase Lakes

Paternoster, or staircase lakes, form by carving out a valley bed of varying resistance of rock to glacial erosion, or by the damming effect of glacial deposits. In the first case, as glaciers move down valley from the zone of accumulation, they erode the bed beneath the ice. Often, the bed or valley is composed of different rock types of varying resistance to erosion. When the glacier encounters weaker rock, it can erode more (deeper) than when it encounters strong, more resistant rock. As a result, depressions are formed in the weak rock, in which water accumulates after the glacier recedes upslope. The lakes are "strung together" by a stream that runs between them. This can be seen by looking at your topographic map below

Figure 8.2 Upvalley view of Green Lakes valley (Photograph used with permission, CULTER http://culter.colorado.edu:1030/ )

The photograph in Figure 8.2 is a view west of lower Green Lakes Valley taken during late June. Lake Albion is in the foreground, with Green Lakes 2 and 1 located above on the left and right hand sides, respectively. Green Lake 3 is visible above Green Lakes 2. Arikaree Glacier lies up valley.

Figure 8. 3 Section of Monarch Lake and Ward USGS topographic maps showing Green Lakes valley. (Contour Interval 40 ft; north is to the top)

Field Journal Entry

Find the tongue-shaped feature (indicated by the letter A in Figure 8.1) protruding into Green Lakes 2 (lake to the northwest of Lake Albion) on the topographic map above. Sketch the shape of the lake and the contour lines into your field journal entry for stop 8.

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Created by Michael Ritter ( mritter@uwsp.edu ) Last revised June 25, 1997