"This till is so tough that engineers would much rather excavate the
most obdurate rocks than attempt to remove it from their path. Hard
rocks are more or less easily assailable with gunpowder, and the
numerous joints and fissures by which they are traversed enable the
workmen to wedge them out often in considerable lumps. But till has
neither crack nor joint; it will not blast, and to pick it to pieces
is a very slow and laborious process. Should streaks of sand
penetrate it, water will readily soak through, and large masses will
then run or collapse, as soon as an opening is made into it."

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TILL OVERLAID WITH BOWLDER-CLAY, RIVER STINCHAR.
_r_, Rock; _t_, Till; _g_, Bowlder-Clay; _x_, Fine Gravel, etc.

The accompanying cut shows the manner in which it is distributed, and
its relations to the other deposits of the Drift.

In this "till" or "hard-pan" are found some strange and
characteristic stones. They are bowlders, not water-worn, not
rounded, as by the action of waves, and yet not angular--for every
point and projection has been ground off. They are not very large,
and they differ in this and other respects from the bowlders found in
the other portions of the Drift. These stones in the "till" are
always striated--that is, cut by deep lines or grooves, usually
running lengthwise, or parallel to their longest diameter. The cut on
the following page represents one of them.

{p. 6}