A valley carved out by a small tributary glacier that joins with a valley carved out by a much larger glacier. The degree to which glaciers
can erode down into the landscape is dictated by their size: the larger the glacier, the deeper the valley it can erode. Thus small glaciers
can erode only shallow valleys while large glaciers can erode much deeper valleys. A hanging valley is a shallow valley carved by a small
glacier and thus the elevation of the valley floor is "hanging" high above the elevation of the valley floor carved out by the larger glacier.
The hanging valley in the top right photo in Glacier National Park contains a waterfall called Bird Woman Falls. A small glacier flowed
out of this valley and joined a larger valley glacier that flowed where Logan Creek is located today. Since this glacier was small compared
to the glacier that carved out the valley occupied by Logan Creek, it was unable to erode down into the landscape very far and a hanging
valley is what you see today. You are looking toward the south-southeast in this photo. On the map, north is toward the top. The photo was
taken from the camera location on the map. The floor of the hanging valley is relatively flat and thus the contour lines on the topographic
map are more widely spaced than those contours representing the sides of the valley. The close spacing of the contour lines at the edge of
the hanging valley indicates a steep drop-off, which is where the waterfall is located.
Photo: K.A. Lemke. Used with permission.
The hanging valley in the bottom right photo is located along Milford Sound on the South Island of New Zealand. The water in the
foreground is part of Milford Sound, a huge U-shaped valley now flooded with sea water. Because the size of a glacier determines
the depth of the valley the glacier can erode, glaciers that flow into the ocean can carve out valleys with bottoms located below
sea level. Glacial troughs filled with sea water are called fjords. The glacier that carved out the hanging valley was smaller
than the glacier that carved out Milford Sound and as a result its valley bottom is at a higher elevation than the bottom of Milford
Sound. Like the hanging valley in Glacier National Park shown above, this hanging valley in New Zealand also has a waterfall where it
joins the main valley.