Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: June 8, 2025
The sandstones and clay of the Keuper resemble the deposits of estuaries and a shallow sea near the land, and afford, in the north-west of Germany, as in France and England, but a scanty representation of the marine life of that period.
Porphyritic tuffs and massive limestone compose the western chain of the Andes above Lima, while in the Oroya Valley we find carbonaceous sandstones. Some of the tuffs may be of the Jurassic age, though the Cretaceous period is also largely represented.
SUBDIVISIONS AND PHYSICAL GEOGRAPHY. The Devonian is represented in New York and southward by the following five series. We add the rocks of which they are chiefly composed. 5 Chemung . . . . . . sandstones and sandy shales 4 Hamilton . . . . . . shales and sandstones 3 Corniferous . . . . . . limestones 2 Oriskany . . . . . . sandstones 1 Helderberg . . . . . . limestones
As there were 21 seams of coal in this intervening mass, the length of time comprised in the interval is not to be measured by the mere thickness of the sandstones and shales. This lower bed is an underclay seven feet thick, with stigmarian rootlets, and the small land-shells occurring in it are in all stages of growth.
We are just as if we were people of Hamburg going to Lubeck by way of Hanover!" I had better have kept my observations to myself. But my geological instinct was stronger than my prudence, and uncle Liedenbrock heard my exclamation. "What's that you are saying?" he asked. "See," I said, pointing to the varied series of sandstones and limestones, and the first indication of slate. "Well?"
The fundamental rocks of the district are grey and red sandstones and shales, with some associated limestones, replete with fossils of the Devonian or Old Red Sandstone group. The volcanoes broke out in the midst of these inclined strata, and when the present systems of hills and valleys had already been formed.
As the lands were worn lower the waste became finer, and during an epoch of transition the Clinton there were deposited various formations of sandstones, shales, and limestones. The Niagara limestones testify to a long epoch of repose, when low-lying lands sent little waste down to the sea.
It was not until the year 1836 that Sir R. Murchison and Professor Sedgwick discovered that the culmiferous or anthracitic shales and sandstones of North Devon, several thousand feet thick, belonged to the coal, and that the beds below them, which are of still greater thickness, and which, like the carboniferous strata, had been confounded under the general name "graywacke," occupied a geological position corresponding to that of the Old Red Sandstone already described.
He noted that the rocky masses of country in the western parts of England generally inclined to the east and south-east; that the red sandstones and marls above the coal measures passed beneath the lias, clay, and limestone, that these again passed beneath the sands, yellow limestones and clays, forming the table-land of the Cotswold Hills, while these in turn passed beneath the great chalk deposits occupying the eastern parts of England.
Shankland or greensand, "a triple alternation of sands and sandstones with clay;" 2. Galt, "a stiff blue or black clay, abounding in shells, which frequently possess a pearly lustre;" 3. Hard chalk; 4. Chalk with flints; these two last being generally white, but in some districts red, and in others yellow.
Word Of The Day
Others Looking