Rift valley

“ Since steep vertical walls, of the height here in question, would make much too great demands on the resistance to pressure of the rocks, inclined gliding planes of slipping are formed simultaneously with the rift, or in place of it, along which the marginal parts of both portions of the block sink into the rift as it opens, to the accompaniment of numerous local earthquakes, so that only a rift-valley of moderate depth is exposed to view, with its floor formed of faulted blocks of the same series of rocks as those which occur in situ high up on the margin of the trough. ”

“ We missed the trail above the alpine pasture and, tying the horses in the firs, blazed our way up the peak. The air was clear of mist on the summit; the cloud was beneath us and we looked out on its gray vapors as one might look upon the sea from an island shore. A rift suddenly disclosed a bit of the valley—a fleeting glimpse, for the dull mass as quickly rolled together again. We congratulated ourselves on the day. You may behold the expanse of land and sky many times from these outlooks, but rarely does it chance that one sees the earth through a cloud rift. ”

“ The block east of the rift moved south and rose, while that to the west was depressed into a tilted and asymmetric basin. Mountain streams flowing eastward to the Atlantic were caught at the base of the rift, and a new set of torrents dashed down the west-facing scarp of the elevated block. After every cloudburst these new streams left their contributions of boulders in screes along the east side of the basin. The gravels steadily increased in thickness, covering the hills and valleys that furrowed the lowland floor. ”

“ Since the African rift valleys seem clearly to be the result of normal faulting resulting from extension of the crust, Heezen and Ewing conclude that the topography of the Mid-Atlantic Ridge is largely the result of normal faulting. Whether the forces are the result of horizontal extension or vertical uplift remains the most important unsolved problem in connection with the origin of the continental as well as the suboceanic rift-valley systems. ”

“ In most places the floor of the trough is completely covered with fragments from the margins of the rift, but naturally, by further widening, the time comes when the free surface of the sima is also exposed. In the case of the great rift-valley of the Red Sea, which, according to Triulzi and Hecker, is already isostatically compensated, development may have gone so far that at the deeper parts the sima is uncovered. With a further separation of the blocks, the pieces broken from the margins remain behind as islands. ”

“ At the head the ravine narrows sharply and leads into a canyon, where the rocky wall rises up on either hand almost perpendicularly to a height of some 700 feet. This rift is about three-quarters of a mile in length, and opens into another valley at the foot of a large glacier which leads to a bay on the coast known as Turnagain Arm. So sharp is the descent that in the course of 22 miles some 900 feet has to be overcome. ”

“ Following these heights westward, a deep rift indicates the course of the stream dividing the valley, and of the highway to Littleton. Between these walls the long ellipse of fertile land beckons us to descend. ”

“ Close by the northern border of the valley we saw, high up above us, a vast rift more than a thousand feet wide in the face of the cliff; and below this the ground was torn into a deep wild channel, and everywhere huge fragments of rock were scattered over the ground. Here it was, then, that the water had poured in—bursting forth from a lake above—by which the city at one stroke had been overwhelmed. Some little notice, by the mighty roaring that must have accompanied so great a crash of rocks and so vast a rush of water, the dwellers in the city must have had ”

“ Not a bush, not a spear of grass; the arid grayish train burns beneath a sun of brass; its débris are scorched to a dull hue, as in a furnace. A ruined mountain is more desolate than any human ruin.
A hundred paces further on, the aspect of the valley becomes formidable. Troops of mammoths and mastodons in stone lie crouching over the eastern declivity, one above another, and heaped up over the whole slope. These colossal ridges shine with a tawny hue like iron rust; the most enormous of them drink the water of the river at their base. ”

“ One break was natural. But that was where an irresistible freshet had driven a way for itself through the rocky barrier of the hills in a boisterous effort to reach and swell the waters of the superior stream. Its achievement was doubtless the work of ages. But it was complete. A deep rift split the face of the gray stone cliffs to a breadth of something over twenty feet.
On the prairie bank the break was a narrow enough opening, barely sufficient for the passage of a horse-drawn vehicle. It had nothing of the naturalness which had split the face of the opposite cliff. ”

“ When three or four miles from Thingvellir, our destination that night, we came to a great rift in the earth known as Hrafna-gjá (Raven's Rift) , a crack going deep down into the earth, and extending three or four miles in a line parallel to another even greater rift that will be again referred to. On reaching Hrafna-gjá, we had to climb down its steep side, there being a drop of something like a hundred feet to the lava at its foot. The steepness and unevenness of the descent rendered it necessary for us all to dismount and lead our ponies down. ”

“ As they entered the grim portal the sun was just touching the horizon, but it occurred to neither of them that it might be pitch dark before they emerged. At first the slant of the rock walls caused one of these to overhang, shutting out the sky, but the rift gradually widening, they could see the brow of these stupendous cliffs, far above against the sky at a dizzy height. ”

“ In driving an extensive level through a hill, at a point 80 fathoms below the summit, they came upon a gigantic rift. A man was let down on a long rope—so tradition reports—and when he had descended to the full extent of it he was unable to see either walls or bottom of the tremendous abyss. We are probably on the track of this monster cavity, an exploration of which will entail labour and fortitude. That and the exploration of the swallet at Hillgrove, when it is opened, are the two most fascinating problems awaiting us in the immediate future. ”

“ There were rifts, valleys, gorges, naked, nearly perpendicular rocks, the faces of mountains, half of which had fallen down in the opposite direction, a snow-filled valley, a winding river with brief blue stretches, a ruined fort on an eminence, a sharp turn, a sudden twilight, and then another blizzard far colder than the last, raging down a lateral ravine, up which, even through the blinding drift, were to be seen, to all seeming higher than mountains of this earth, the twin peaks of Shamran lighted by the sun. ”

“ In the Cañon Country the snow had disappeared from most of the high points. Red, black, yellow, the great face of the encircling Wall stood in everlasting majesty, looking down upon the level cup of Lost Valley. The unspeakable upheaval of peaks and crags, of cañons and splits and unfathomable depths, was almost a sealed book to the denizens of the Valley. There were those who knew False Ridge.
There were those who said they knew more. Many a man had adventured therein, and few had returned to tell of their adventures. ”

“ In valleys where they have been rashly cut away, and the waters pour down the slopes unchecked, every tiny rivulet becomes a raging torrent, that carries off the grassy slopes and devastates the floor of the valley, covering the soil with gravel and debris. ”

“ Far away, it is true, from one broad solitary rift, he could see the sunlight pouring on to Helvellyn and tinting its white slopes to a sheet of gold. But there were black masses clustered close above it, as if jealous of its glow, and even as he watched, the rift closed up and the snow was discoloured to a dull, cheerless grey. ”

“ Had it not been for the predicament in which they had left the professor and Coyote Pete, the three lads would have felt a real interest in exploring the cavern, now that they had grown accustomed to their surroundings. So far as they had been able to make out, the tunnel they had been treading was partially the work of human hands and partially the work of Nature. The great rift in which lay the accumulation of human remains was evidently the result of some volcanic upheaval. ”

“ Although they had recently passed through some very arduous experiences these were only looked on as vague reminiscences by these energetic chums. The future beckoned with rosy fingers and that level plain looked very attractive in their eyes, after such a long and painful trip across the burning deserts and through that terrible Death Valley, where so many venturesome prospectors, gold-mad, have left their bones as a monument to their folly. ”

“ A scramble over a rough slide of loose sandstone at the upper end of the valley, a treacherous sloping ledge of rock overhanging an awkward precipice, and a steep ravine which brings into play all one's gymnastic capabilities, leads to an extensive plateau broken up by many deep ravines and rising knolls. On one of the highest of these last is a heap of ruins—hewn sandstone walls, with broken columns, and numerous stelæ, in shape like ordinary English gravestones, standing or scattered at irregular intervals about the place, the whole being surrounded by the debris of an outer-wall. ”

“ The shattered fronts of walls stand out sharp and terrible, sweeping down in broken crag and cliff to a valley whereon the shadow of autumnal death has left its solemnity. There is no longer an air of beauty. In this cold, naked strength, one has crowded on him the geological record of mountain work, of granite plateau suddenly rent asunder, of the slow, imperfect manner in which Nature has vainly striven to smooth her rough work and bury the ruins with thousands of years’ accumulation of soil and débris. ”

“ One does not understand why rocks and landslides do not plunge down these declivities daily. A landslip occurred three quarters of a century ago, on the route from Arth to Brunnen, which was a formidable thing. A mass of conglomerate two miles long, a thousand feet broad, and a hundred feet thick, broke away from a cliff three thousand feet high and hurled itself into the valley below, burying four villages and five hundred people, as in a grave. ”

“ We are in the rocks, you’ll notice. There is not a grain of dirt near us. This accounts for the hole’s not filling up with debris and disappearing through all these years. It’s been gouged with infinite pains in comparatively solid stone. It’s conclusive now that at one time the Valley of Arcana was inhabited and was the scene of tribal warfare. That was doubtless years before the fire swept down the forest and the chaparral locked the valley against intrusion. ”

“ We went to the Öxerá, explored the deep rift between the walls, which in places has been fenced off for sheep cotes. We climbed the wall to the top of the falls, peered down into the numerous fissures and were astonished to find snow at the bottom of one of them. It is a narrow chasm, very deep and the sun can not reach the bottom. We followed the wall eastward for two miles where we found a place to descend into the plain. On the return we wandered among the crevasses, dodging blocks of lava and jumping the narrow rifts where down a hundred feet the water glimmered. ”

“ On one side was a rock, forming a wall rugged and projecting above; at the bottom of the rock was a rift, somewhat resembling a coffin in shape, and not much larger in dimensious: this rift terminated on the opposite side of the rock in an opening that was too small for the body of a man to pass: the distance between each entrance was twice the length of a man. ”

“ Now that Sands and Allie Lane were together again, how were they to escape from the underground outpost of Jupiter? If we did succeed in finding our way out of the maze of tunnels, how did we expect to traverse Death Valley without water? It was impossible! Better had we all remain hidden far below Death Valley's burning surface than to expose ourselves to the sinister power of Abaris or the terrible fatal heat of the surface! ”

“ This view of the matter is proved by the fact, that the numerous cracks, rents, or fissures, such as those around the Althing, with which the valley is intersected, when examined are 90found exactly to correspond in their sections—trahytic trap capped by lava—with the edges left standing as they were before the subsidence of the valley and now bounding it like a black rampart. The pastor’s dwelling, from where I stand, presents the appearance of a few grass hillocks or potato-pits. The site of each erection is partly excavated from the side of a little slope, to protect it from the storm. ”

“ As the escarpment of the rift is approached the character of the landscape changes completely. The trees, the flowers, and the birds disappear, and a barren expanse, or table-land, of lava, interspersed by black and jagged rocks, extends to the very summit of the cliffs. The scene here is a remarkable one. The surface of the plateau is seamed by the inverted cones of extinct craters, many hundred feet in depth, close to one another, and frequently separated only by a ridge a few yards in width at the top. ”

“ Amid the beauty of the most uncultivated and untrodden wilderness there are certain localities where the meaner and mere common processes of Nature take upon themselves a degrading likeness to the slovenly, wasteful, and improvident processes of man. The unrecorded land-slip disintegrating a whole hillside will not only lay bare the delicate framework of strata and deposit to the vulgar eye, but hurl into the valley a debris so monstrous and unlovely as to shame even the hideous ruins left by dynamite, hydraulic, or pick and shovel ”