From a book called “Glacier Ice” Austin Post and Edward R.Lachapelle tell us about the congruent glaciers in the Yukon. Here is a photo and an explanation of what is happening with these glaciers.

They originate from very similar firn basins and flow along nearly identical parallel valleys. The one on the left has recently advanced. Its thick, bulging terminus overrides debris in the valley floor, while the thickening edges accumulate a rock mantle from the adjacent valley walls. The center glacier also advanced, but now recedes and has been doing so for a number of years. The rock mantle along each side has been deposited as lateral moraines, ridges of unconsolidated material paralledl to the glacier flanks. The third “Congruent Glacier” appears to have made a very recent advance from which it has not yet begun to retreat. Faint trimlines considerably higher up the valley walls than the present ice levels indicate that all three glaciers have at one time advanced much farther than their positions today.

Return to “New Denver Glacier” page.