g. E., in the path of the reflux of the Agulhas
current, than in long. 108 deg. E.

"All along the edge of the ice-pack--everywhere, in fact, to the south of
the two stations--on the 11th of February on our southward voyage, and on
the 3rd of March on our return, we brought up fine sand and grayish mud,
with small pebbles of quartz and felspar, and small fragments of mica-
slate, chlorite-slate, clay-slate, gneiss, and granite. This deposit, I
have no doubt, was derived from the surface like the others, but in this
case by the melting of icebergs and the precipitation of foreign matter
contained in the ice.

"We never saw any trace of gravel or sand, or any material necessarily
derived from land, on an iceberg. Several showed vertical or irregular
fissures filled with discoloured ice or snow; but, when looked at
closely, the discoloration proved usually to be very slight, and the
effect at a distance was usually due to the foreign material filling the
fissure reflecting light less perfectly than the general surface of the
berg. I conceive that the upper surface of one of these great tabular
southern icebergs, including by far the greater part of its bulk, and
culminating in the portion exposed above the surface of the sea, was
formed by the piling up of successive layers of snow during the period,
amounting perhaps to several centuries, during which the ice-cap was
slowly forcing itself over the low land and out to sea over a long extent
of gentle slope, until it reached a depth considerably above 200 fathoms,
when the lower specific weight of the ice caused an upward strain which
at length overcame the cohesion of the mass, and portions were rent off
and floated away. If this be the true history of the formation of these
icebergs, the absence of all land _debris_ in the portion exposed above
the surface of the sea is readily understood. If any such exist, it must
be confined to the lower part of the berg, to that part which has at one
time or other moved on the floor of the ice-cap.

"The icebergs, when they are first dispersed, float in from 200 to 250
fathoms. When, therefore, they have been drifted to latitudes of 65 deg. or
64 deg. S., the bottom of the berg just reaches the layer at which the
temperature of the water is distinctly rising, and it is rapidly melted,
and the mud and pebbles with which it is more or less charged are
precipitated. That this precipitation takes place all over the area where
the iceber