Accordingly, I found that the edge of the ice round this clear
area was much thicker than the rest of the ice of the floor, and was
evidently the remains of the swelling pedestal of a column which had
been about 12 feet in circumference. This departed column may account
for a fact which I discovered in another glaciere, and found to be of
very common occurrence, viz., that in large stalagmites there is a
considerable internal cavity, extending some feet up from the ground,
and affording room even for a man to walk about inside the column.
When the melted snows of spring send down to the cave, through the
fissures of the rock, an abundance of water at a very low
temperature, and the cave itself is stored with the winter's cold,
these thicker rings of ice catch first the descending water, and so a
circular wall, naturally conical, is formed round the area of stones;
the remaining water either running off through the interstices, or
forming a floor of ice of less thickness, which yields to the next
summer's drops. In the course of time, this conical wall rises,
narrowing always, till a dome-like roof is at length formed, and
thenceforth the column is solid.
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