V-shaped valley
| Title | Info |
|---|---|
| Source | Dan L. Perlman |
| Ecosystems | Other |
| Disturbance | Glacier |
| Geography and geology | Glacial meltwater-created valley |
| Date | October 07, 2005 |
| Location | Blue Hills Felsenmeer State Natural Area,Rusk County,Wisconsin,USA,North America |
Glacial meltwater effects: a V-shaped valley, Wisconsin. This steep-sided valley was apparently created by meltwater from the Wisconsinan Glaciation about 15-20,000 years ago. The east-west orientation of the valley has led to extreme microclimate differences between the two slopes, as can be seen in the Related materials.
The sides of this east-west oriented valley are covered with broken rock (or talus slopes); the German term felsenmeer refers to a "sea of rocks" (although the slopes of this valley are steeper than a typical felsenmeer). Because the two sides of the valley receive very different amounts of sunlight, they experience very different temperature and moisture regimes. The largely barren south-facing slope is much hotter and dryer than the north-facing slope, which is covered by mosses, ferns, and lichens. The boulders on the shaded side remain especially cool because cold air from deep underground gently wafts up to the surface. It appears that a number of the plant and lichen species on the shady side are typical of regions far to the north of this site.
Recent studies indicate that this steep-sided valley was carved by meltwater from a glacial lake created at the time of the Wisconsinan Glaciation about 15-20,000 years ago. Since then, the freeze/thaw cycles experienced by the bare rock lining the valley has created the loose head-sized boulders seen here.
