From time to time, one or more of the glaciers has surged forward for a few years, then resumed its general retreat. The Chatham Strait fault nearly bisects the image from top to bottom slightly oblique to the 135th west meridian. Elias fault has formed a zone of crushed and weakened rocks parallel to the coast across the southwest corner of the scene. Erosion by rivers and glaciers has carved deep trough- like valleys along the tectonic lineaments. Some valleys extend radially from the centers of the large Glacier Bay and Taku Ice Fields.
Fjords are glacier troughs, eroded below sea level and now submerged.
Tides in Glacier Bay range up to 7 m in amplitude. The combination of deep fjords, powerful tidal currents, and very recent deglaciation has produced a coastal landscape devoid of any depositional landforms except for outwash deltas at the fronts of some retreating glaciers. There are almost no beaches except for gravel pockets in coves. C-5.4 It is typical of tectonic coasts to have strong structural lineations, in this region accentuated by glacial erosion. We now interpret Suess's Pacific-type coasts as typical of converging plate margins, where active tectonic compression is deforming the edge of the continental crust.