These were extremely
brittle, the slightest blow with a stick, or with each other, being
sufficient to break them short off; and when taken into the hand, many of
them broke to pieces with their own weight.
On being broken transversely, it was immediately seen that the internal
part was divided into interior or central, exterior or cortical. The
exterior part, which in different specimens occupied various proportions
of the whole, resembled a fine white and soft grit-stone; but acids being
applied, showed it to be combined with a considerable portion of
calcareous matter. The interior or central part was always circular, but
seldom found of the same diameter, or of the same composition, on any two
stumps. In some the calcareous and sandy matter had taken such entire
possession, that every fragment of the wood was completely obliterated;
but yet a faint central ring remained. In others was a centre of chalk,
beautifully white, that crumbled between the fingers to the finest
powder; some consisted of chalk and brown earth, in various quantities,
and some others had detained a few frail portions of their woody fibres,
the spaces between which were filled up with chalky earth.
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