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The longest continuous fault has been traced three hundred and seventy-five miles, and the greatest horizontal displacement has been estimated at not less than eleven miles. CRUSH BRECCIA. Rocks often do not fault with a clean and simple fracture, but along a zone, sometimes several yards in width, in which they are broken to fragments.
There are, it is true, near the mouths of the great Siberian rivers which empty themselves into the Polar Sea, drift islands composed, in an incredibly large proportion, of the bones and tusks of elephants, mastodons, and other huge pachyderms, and many extensive caves in various parts of the world are half filled with the skeletons of quadrupeds, sometimes lying loose in the earth, sometimes cemented together into an osseous breccia by a calcareous deposit or other binding material.
Near Cumana the formation of the calcareous breccia contains: first, a compact whitish grey limestone, the strata of which, sometimes horizontal, sometimes irregularly inclined, are from five to six inches thick; some beds are almost unmixed with petrifactions, but in the greatest part the cardites, the turbinites, the ostracites, and shells of small dimension, are found so closely connected, that the calcareous matter forms only a cement, by which the grains of quartz and the organized bodies are united: second, a calcareous sandstone, in which the grains of sand are much more frequent than the petrified shells; other strata form a sandstone entirely free from organic fragments, yielding but a small effervescence with acids, and enclosing not lamellae of mica, but nodules of compact brown iron-ore: third, beds of indurated clay containing selenite and lamellar gypsum.
The pair of beautiful Grecian Ionic columns, and the large green tazza eighteen feet in circumference the finest specimen of Egyptian breccia to be seen in Rome, both in the Villa Albani, and the vase of the same material in the chamber of Candelabra in the Vatican, in which the prevailing green colour is crossed by several stripes of pure white quartz, may thus have been sculptured out of a portion of littoral deposit formed from the ruins of the crystalline rocks of the mountain group of Sinai.
Schmerling in a sufficient state of integrity to enable the anatomist to speculate on the race to which it belonged, was buried 5 feet deep in a breccia, in which the tooth of a rhinoceros, several bones of a horse, and some of the reindeer, together with some ruminants, occurred. On the right bank of the Meuse, on the opposite side of the river to Engis, is the cavern of Engihoul.
It may occur also that strata which as a whole yield to lateral thrust by folding include beds of brittle rocks, such as thin-layered limestones, which are crushed to pieces by the strain. Breccia is a term applied to any rock formed of cemented ANGULAR fragments.
Down such swallow-holes how many beasts must fall: either in hurry and fright, when hunted by lions and bears and such cruel beasts; or more often still in time of snow, when the holes are covered with drift; or, again, if they died on the open hill-sides, their bones might be washed in, in floods, along with mud and stones, and buried with them in the cave below; and beside that, lions and bears and hyaenas might live in the caves below, as we know they did in some caves, and drag in bones through the caves' mouths; or, again, savages might live in that cave, and bring in animals to eat, like the wild beasts; and so those bones might be mixed up, as we know they were, with things which the savages had left behind like flint tools or beads; and then the whole would be hardened, by the dripping of the limestone water, into a paste of breccia just like this in my drawer.
When all the angular fragments are of volcanic rocks the mass is usually termed a volcanic breccia. Laterite is a red or brick-like rock composed of silicate of alumina and oxide of iron. The red layers called "ochre beds," dividing the lavas of the Giant's Causeway, are laterites. These were found by Delesse to be trap impregnated with the red oxide of iron, and in part reduced to kaolin.
The columns are antique, but of varied material cipollino, white and black and white-veined marble, and granite; and there is one of a rosy and white breccia. The caps vary both in design and size, and have been repaired with stucco. Some of them are decadent Roman and the rest Byzantine: the bases are hidden by a square wooden boxing. The eleven arches of the nave arcade are round.
But it has been suggested in explanation that such serpentine may have been originally regularly-bedded trap tuff, and volcanic breccia, with much olivine, which would still retain a stratified appearance after their conversion into a metamorphic rock.
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