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Updated: June 8, 2025
But how came these tertiary sandstones to be so very hard, while the strata around them are so soft? Ladies and gentlemen, I know no more than you. Experience seems to say that stone will not harden into that sugary crystalline state, save under the influence of great heat: but I do not know how the heat should have got to that layer in particular. However, I have no proof that this was the cause.
There are sandstones, such, for example, as are used for grindstones, where the grit, as it is called, is of exceeding sharpness; others where the angles of the grains are so obtuse that they scarcely act at all on hard metals.
Leaving El Tovar promptly at 8:30 A. M., fortified with a good breakfast, and suitably clothed, the trail party in a few minutes reaches the head of Bright Angel Trail near Bright Angel Camp. For three-quarters of a mile this trail descends, zigzagging back and forth until the top of the cross-bedded sandstone is reached. Faulting in the Sandstones.
Where the trampled slope rose from the creek I came upon a small but solid house, built of gray and ruddy sandstones, a quaint, shell-curved penthouse above the open doorway. Here were horses held by orderlies, the blue and white of French uniforms, buff-and-blue officers, and the guard of fifty light horse on a side road in the saddle, facing the house. I knew I had found the headquarters.
IMPERVIOUS ROCKS, such as granite, clay, and shale, have pores so minute that the water which they take in is held fast within them by capillary attraction, and none drains through. PERVIOUS ROCKS, on the other hand, such as many sandstones, have pore spaces so large that water filters through them more or less freely.
It might be worth while to experiment upon some of the porous sandstones, which, under the extreme influence of our climate, rapidly deteriorate; such, for instance, as the Connecticut sandstone, so popular at one time as a building material, but which is now generally discarded, owing to its tendency to crumble to pieces when exposed to the weather even for a few years.
While the men are at work making portages, I climb up the granite to its summit, and go away back over the rust-coloured sandstones and greenish-yellow shales to the foot of the marble wall. I climb so high that the men and boats are lost in the black depths below, and the dashing river is a rippling brook; and still there is more cañon above than below.
It has already been stated that the Carboniferous or Mountain Limestone underlies the coal-measures in the South of England and Wales, whereas in the North, and in Scotland, marine calcareous rocks partly of the age of the Mountain Limestone alternate with shales and sandstones, containing seams of coal.
Its position, above the sandstones of the Sewalik range in the north-west Himalaya, and those of Sikkim, which appear to be modern fossiliferous rocks, indicates its being geologically of recent formation; but it still remains a subject of the utmost importance to discover the extent and nature of the ocean to whose agency it is referred.
In places the bed of the river is of sandstone or limestone, in other places of lava, showing that it has all been cut out again where the sandstones and limestones appear; but there is a little yet left where the bed is of lava. What a conflict of water and fire there must have been here! Just imagine a river of molten rock, running down into a river of melted snow.
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