Observing one large hummock to be very much discoloured, we found, on
approach, that this discolouration was caused by the adhesion of mud or
clay, a line of which extended for some distance along the edge of the
floe, and gave one the idea that it had rubbed against, or in some
manner had come into contact with, the shore. Mud it undoubtedly was,
and we bottled a quantity of it for the purpose of subjecting it to
microscopic investigation when we should return on board. This was
conclusive evidence that a periodical, if not an annual, disruption of
the pack occurs, and that these floes, although now at such a distance
from the land, had at some time or another been in very close
proximity. Moreover, this must have occurred at a recent date,
otherwise the summer thaws and the autumn snow would have obliterated
all such traces as those we had discovered.