Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 25, 2025
The space between this bank and the true shore consists of the sedimentary deposits from these and other rivers, a great plain of calcareous mud, covered, in the neighborhood of Venice, by the sea at high water, to the depth in most places of a foot or a foot and a half, and nearly everywhere exposed at low tide, but divided by an intricate network of narrow and winding channels, from which the sea never retires.
The Tokay Eperies group of hills is one of several well-defined groups of volcanic rocks that exist in Hungary and Transylvania. In the Tokay district the formations are partly eruptive, partly sedimentary, but nowhere older than the Tertiary period, say the geologists.
We can therefore safely come to the conclusion that the large masses of encrinital limestone, which attain such an enormous thickness in some places, especially in Ireland, have been formed far away from the land of the period; we can at the same time draw the conclusion that if we find the encrinites broken and snapped asunder, and the limestone deposits becoming impure through being mingled with a proportion of clayey or sandy deposits, that we are approaching a coast-line where perhaps a river opened out, and where it destroyed the growth of encrinites, mixing with their dead remains the sedimentary dêbris of the land.
When the exposed land consists of several unlike kinds of sedimentary strata, or igneous rocks, or both, denudation produces changes proportionably more heterogeneous. The formations being disintegrable in different degrees, there follows an increased irregularity of surface.
Whence it follows, that sedimentary strata passing a certain antiquity, are unlikely to be found in an unmetamorphosed state; and that strata much earlier than these are certain to have been melted up.
Over the great mineral belt which lies between the Sierra Nevada and the front range of the Rocky Mountains, and extends not only across the whole breadth of our territory, but far into Mexico, the surface was once underlain by a series of Palaeozoic sedimentary strata not less than twenty to thirty thousand feet in thickness; and beneath these, at the sides, and doubtless below, were Archæun rocks, also metamorphosed sediments.
Who can avoid wondering at the force which has upheaved these mountains, and even more so at the countless ages which it must have required to have broken through, removed, and levelled whole masses of them? It is well in this case to call to mind the vast shingle and sedimentary beds of Patagonia, which, if heaped on the Cordillera, would increase its height by so many thousand feet.
Sedimentary rocks are divided into the fragmental rocks which are made of fragments, either coarse or fine and the far less common rocks which are constituted of chemical precipitates. The sedimentary rocks are divided according to their composition into the following classes: 1. The calcareous, or lime rocks, including limestone and a soft white rock formed of calcareous powder known as chalk.
It was the sedimentary deposit thus formed which was to fertilise the soil of patriotism which had grown so barren in the civil wars.
The expiring energies of these volcanic agencies have piled up huge cinder cones that stand along the fissures, red, brown, and black, naked of vegetation, and conspicuous landmarks, set as they are in contrast to the bright, variegated rocks of sedimentary origin.
Word Of The Day
Others Looking