p. 4

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I am disposed to rank it [No. 3] with
the next [Lacustrine deposites] though
is apparently older, and originated
in a much larger body of water.

Many facts respecting
the present distribution of the boulders
will be understood and explained
by the consideration of the effects
of erosion.

[Illustration]

Let the line a, represent the original surface of the drift, and b,
the surface after a considerable erosion
in which a deep ravine has been formed.
The boulders originally lying in the removed portion of
the drift, being more ponderous than the other
materials, have not been carried away, but will
be found lying upon the new surface and
accumulated along the bottom of the ravine.
These last by protecting the softer materials below
cause a ridge to be left (as the erosion progresses) shown in the figure by the
final surface line c.
Such accumulations of
boulders in lines, may account for some of the
so called moraines.

I fear your profile may give a false
impression, by representing boulders only