A Manual of Elementary Geology: or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological MonumentsLyell, Charles, Sir
Science
A Manual of Elementary Geology: or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments
Lyell, Charles, Sir
Geology
Early in the year 1851, Mr. Logan laid before the Geological Society of
London a slab of this sandstone from Beauharnais, containing no less than
twenty-eight foot-prints of the fore and hind feet of a quadruped, and six
casts in plaster of Paris, exhibiting a continuation of the same trail.
Each cast contained from twenty-six to twenty-eight impressions with a
median channel equidistant from the two parallel rows of foot-prints, the
one made by the feet of the right side, the other by those of the left. In
these specimens a greater number of successive foot-marks belonging to one
and the same series were displayed than had ever before been observed in
any rock ancient or modern. Mr. Abraham has inferred that the breadth of
the quadruped was from five to seven inches. A detailed account of the
trail was published by Professor Owen, in April 1851, from which the
following extracts are made.
"The foot-prints are in pairs, and the pairs extend in two parallel series,
with a channel exactly midway between the right and left series. The pairs
of the same side succeed each other at intervals, varying from one inch and
a half to two inches and a half, the common distance being about two
inches. The interval between the right and left pairs, measured from the
inner border of the small prints, is three inches and a half, and from the
outer border of the exterior or large prints, is seven inches. The shallow
median track is one inch and a quarter in breadth, varying in depth, but
not in its relative position to the right and left foot prints."
"The inference to be deduced from these characters is, that the impressions
were made by a quadruped with the hind feet larger and somewhat wider apart
than the fore feet, with both hind and fore feet either very short, or
prevented by some other part of the animal's structure from making long
steps; and with the limbs of the right side wide apart from those of the
left; consequently, that the quadruped had a broad trunk in proportion to
its length, supported on limbs either short, or capable only of short
steps, and with rounded and stumpy feet, not provided with long claws.
There are faint traces of a fine reticulate pattern of the cuticle of the
sole at the bottom of some of the foot-prints on one portion of the
sandstone; and the surface of the sand is generally smoother there than
where not impressed, which, with the rising of the sand at the border of
the prints, indicates the weight of the impressing body. The median groove
may be interpreted as due either to the abdomen or the tail of the animal;
but as there is no indication of any bending or movement of a tail from
side to side, it was probably scooped out of the soft sand by a hard
breast-plate or plastron. If this were so, it may be inferred that
the species was a freshwater or estuary tortoise rather than
a land tortoise."[viii-A]
Public-domain text, read in full here on John Shaqi.
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