This great body of ice was thrust up on the side of Mussen Mountain by a lateral movement of ice years ago. A small stream from the mountain-side cut a channel through the ice where the arch is now, then took a lower course as the ice receded, leaving the arch to its own destiny. A heavy deposit of morainic material protects the upper part from the action of warm winds and sun but underneath the arch there is no such protection and the space has increased from year to year. For several years I had noted this ice but had no idea of its real nature. I remember seeing, some years ago, a stream of water coming through what must now be the arch, but, being about a half mile away, it was so hidden that I paid no attention to it

LLEWELLYN MOUNTAIN ARCH OF ICE, VIEWED FROM THE SOUTH

This arch is located about a half mile back from the ground moraine, near the present moat or space between the ice and the mountain-side (see
page 620 for detail of moat). The ice evidently has been receding along this moat in the last few years. I am convinced, however, that the rate of
flow of this glacier as a whole is slow. The great bed of the glacier does not seem to have advanced or retreated to any considerable extent since my
first trip in 1911. I think that one hundred feet would cover all the recession. There is abundant evidence, however, that it has made a great retreat
at some recent period, as the willows and alders show that their growth does not extend beyond twenty or twenty-five years. There are no forest

trees on the present ground moraine.

The region of alimentation of Llewellyn Glacier is about halfway between the south end of Atlin Lake and Taku Glacier on the Pacific coast, estimated three days' travel by the Indians, seventy-five miles by white prospectors. The ice is continuous from Llewellyn Glacier to Taku Glacier. Llewellyn Glacier evidently ought to be classed as a through-mountain glacier of piedmont type. I cannot ascertain that the earthquake of 1899 had the effect of advancing this glacier, as it did the Hidden and others on the Alaska coast