On The Older Portions Of This Moraine I Discovered Several Kettles In
Process Of Formation And Was Pleased To Find
That they conformed in
the most striking way with the theory I had already been led to make
from observations
On the old kettles which form so curious a feature
of the drift covering Wisconsin and Minnesota and some of the larger
moraines of the residual glaciers in the California Sierra. I found
a pit eight or ten feet deep with raw shifting sides countersunk
abruptly in the rough moraine material, and at the bottom, on sliding
down by the aid of a lithe spruce tree that was being undermined, I
discovered, after digging down a foot or two, that the bottom was
resting on a block of solid blue ice which had been buried in the
moraine perhaps a century or more, judging by the age of the tree
that had grown above it. Probably more than another century will be
required to complete the formation of this kettle by the slow melting
of the buried ice-block. The moraine material of course was falling
in as the ice melted, and the sides maintained an angle as steep as
the material would lie. All sorts of theories have been advanced for
the formation of these kettles, so abundant in the drift over a great
part of the United States, and I was glad to be able to set the
question at rest, at least as far as I was concerned.
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