So long as the epidermis of animals remains sound, disease germs may come in contact with it almost with impunity, but immediately on its being fissured, or a larger wound made through it, the underlying parts, the blood and soft tissues, are attacked by them.
In this system the soft ground or fissured water-bearing rock is rendered temporarily solid by freezing the contained water within a surface a few feet larger in diameter than the size of the finished shaft, so that the ground may be broken either by hand tools or blasting in the same manner as hard rock.
M.; the circuit of its walls, which are composed of a hard grey clinkstone much fissured, is 20 m.; its greatest depth is 2720 ft.
The great rivers which flow eastward to the sea have fissured and moulded the surface into deep ravines alternating with high plateaus, ridges and isolated hills.
Among the sedimentary rocks we have, for example, in the clay slates of the Silurian formations, rocks no less cracked and fissured than others, but generally quite impermeable by reason of the joints being packed with the very fine clay resulting from the rubbing of slate upon slate in the earth movements to which the cracks are due.
The lowest part of the surface of this rock was reached after excavating through alluvial deposits to a depth of about 70 ft., but owing to its fissured and cavernous nature it became necessary to excavate to much greater depths, reaching in places more than 120 ft.
On account of the small amount of precipitation, the fissured condition of the underlying lava sheets, and the porous soil, the Great Sandy Desert has practically no surface streams even in the wet season, and within its limits no potable waters have been found.