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Updated: May 24, 2025
If their deductions be true; we have in Luray a cavern that was fifty-four thousand years old when Adam gazed on Paradise. These caverns are carved from the Silurian limestone, although they are considered to date from the Tertiary period.
CORALS developed along several distinct lines, like modern corals they secreted a calcareous framework, in whose outer portions the polyps lived. In the Ordovician, corals were represented chiefly by the family of the CHOETETES, all species of which are long since extinct. The description of other types of corals will be given under the Silurian, where they first became abundant.
The characters of the Upper and Lower Silurian rocks were established so fully, both on stratigraphical and palaeontological data, by Sir Roderick Murchison after five years' labour, in 1839, when his "Silurian System" was published, that these formations could from that period be recognised and identified in all other parts of Europe and in North America, even in countries where most of the fossils differed specifically from those of the classical region in Britain, where they were first studied.
Contemporaneously with these observations, the indefatigable Ehrenberg had discovered that the "greensands" of the geologist were largely made up of casts of a similar character, and proved the existence of Foraminifera at a very ancient geological epoch, by discovering such casts in a greensand of Lower Silurian age, which occurs near St. Petersburg. Subsequently, Messrs.
True, the billiard-tables were of the Old Silurian Period, and the cues and balls of the Post-Pliocene; but there was refreshment in this, not discomfort; for there is rest and healing in the contemplation of antiquities. The most notable absence observable in the billiard-room, was the absence of the river man. If he was there he had taken in his sign, he was in disguise.
Powrie to be the eggs of crustaceans, which is highly probable, for they have not only been found with Pterygotus anglicus in Forfarshire and Perthshire, but also in the Upper Silurian strata of England, in which species of the same genus, Pterygotus, occur.
The fundamental rocks of this region belong to the Silurian, Devonian, and Carboniferous systems, consisting of schists, grits, and limestones, with occasional horizontal beds of Miocene sandstone and shale with lignite, resting on the upturned edges of the older rocks.
When the term Silurian was given by Sir R. Murchison, in 1835, to the whole series, he considered the Stiper-Stones as the base of the Silurian system, but no fossil fauna had then been obtained, such as could alone enable the geologist to draw a line between this member of the series and the Llandeilo flags above, or a vast thickness of rock below, which was seen to form the Longmynd hills, and was called "unfossiliferous graywacke."
The CoeLENTERATA. The Tabulate Corals have existed from the Silurian epoch to the present day, but I am not aware that the ancient Heliolites possesses a single mark of a more embryonic or less differentiated character, or less high organization, than the existing Heliopora.
Nor should we be justified in assuming that if, for instance, the bed of the Pacific Ocean were now converted into a continent, we should there find formations older than the silurian strata, supposing such to have been formerly deposited; for it might well happen that strata which had subsided some miles nearer to the centre of the earth, and which had been pressed on by an enormous weight of superincumbent water, might have undergone far more metamorphic action than strata which have always remained nearer to the surface.
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