Beside this stone now lies another of the purest white.  It once flowed as water impregnated with lime, and clung to the lower side of a rock now as high above the sea as many a famous mountain.  The water gradually evaporated, and the lime still hung like tiny drops.  Between the two stones now so near together was once a perpendicular distance of more than a mile of impenetrable rock.  How did they ever get together?  Let us see.

After the rock making, by the deposit of clay, limestone, etc., this vast plain was lifted seven thousand feet above the sea and rimmed round with mountains.  Perhaps in being afterward volcanically tossed in one of this old world’s spasms an irregular crack ripped its way along a few hundred miles.  Into this crack rushed a great river, perhaps also an inland ocean or vast Lake Superior, of which Salt Lake may be a little remnant puddle.  These tumultuous waters proceeded to pulverize, dissolve, and carry away these six thousand feet of rock deposited between the two stones.  There was fall enough to make forty Niagaras.

I was once where a deluge of rain had fallen a few days before in a mountain valley.  It tore loose some huge rocks and plunged down a precipice of one thousand feet.  The rock at the bottom was crushed under the frightful weight of the tumbling superincumbent mass, and every few minutes the top became the bottom.  In one hour millions of tons of rock were crushed to pebbles and spread for miles over the plain, filling up a whole village to the roofs of the houses.  I knew three villages utterly destroyed by a rush of water only ten feet deep.  Water and gravitation make a frightful plow.  Here some prehistoric Mississippi turned its mighty furrows.

The Colorado River is one of our great rivers.  It is over two thousand miles long, reaches from near our northern to beyond our southern border, and drains three hundred thousand square miles of the west side of the Rocky Mountains.  Great as it remains, it is a mere thread to what it once was.  It is easy to see that there were several epochs of work.  Suppose the first one took off the upper limestone rock to the depth of several thousand feet.  This cutting is of various widths.  Just here it is eighteen miles wide; but as such rocks are of varying hardness there are many promontories that distinctly project out, say, half a mile from the general rim line, and rising in the center are various Catskill and Holyoke mountains, with defiantly perpendicular sides, that persisted in resisting the mighty rush of waters.  The outer portions of their foundations were cut away by the mighty flood and, as the ages went by, occasionally the sides thundered into the chasm, leaving the wall positively perpendicular.

We may now suppose the ocean waters nearly exhausted and only the mighty rivers that had made that ocean were left to flow; indeed, the rising Sierras of some range unknown at the present may have shut off whole oceans of rain.  The rivers that remained began to cut a much narrower channel into the softer sand and clay-rock below.  From the great mountain-rimmed plateau rivers poured in at the sides, cutting lateral canons down to the central flow.  Between these stand the little Holyokes aforesaid, with greatly narrowed base.