Granite Moraine

"Strange to say, these boulders lying so still and deserted, with no moving force near them, no boulder carrier anywhere in sight, were nevertheless brought from a distance, as difference in color and composition shows, quarried and carried and laid down here each in its place; nor have they stirred, most of them, through calm and storm since first they arrived. They look lonely here, strangers in a strange land,--huge blocks, angular mountain chips, the largest twenty or thirty feet in diameter, the chips that Nature has made in modeling her landscapes, fashioning the forms of her mountains and valleys. And with what tool were they quarried and carried? On the pavement we find its marks. The most resisting unweathered portion of the surface is scored and striated in a rigidly parallel way, indicating that the region has been overswept by a glacier from the northeastward, grinding down the general mass of the mountains, scoring and polishing, producing a strange, raw, wiped appearance, and dropping whatever boulders it chanced to be carrying at the time it was melted at the close of the Glacial Period. A fine discovery this." -John Muir


Moraine is any glacial debris of soil or rock. It can be as small as silt or as large as the granite monoliths of Yosemite.

Silt moraine in Yosemite provides some of the best soil in the world. John Muir sums up the process: "As for the forests we have been passing through, they are probably growing on deposits of soil most of which has been laid down by this same ice agent in the form of moraines of different sorts, now in great part disintegrated and outspread by post-glacial weathering."

And enormous moraine boulders in Yosemite are the largest granite monoliths in the world: "The great Tissiack, or Half-Dome, rising at the upper end of the valley to a height of nearly a mile, is nobly proportioned and life-like, the most impressive of all the rocks, holding the eye in devout admiration, calling it back again and again from falls or meadows, or even the mountains beyond,--marvelous cliffs, marvelous in sheer dizzy depth and sculpture, types of endurance. Thousands of years have they stood in the sky exposed to rain, snow, frost, earthquake and avalanche, yet they still wear the bloom of youth."

Muir had quite a bit to say about the moraines of stunning Tenaya Lake: 

"All is bare, shining granite, suggesting the Indian name of the lake, Pywiack, meaning shining rock. The basin seems to have been slowly excavated by the ancient glaciers, a marvelous work requiring countless thousands of years."

"Arriving early, I took a walk on the glacier-polished pavements along the north shore, and climbed the magnificent mountain rock at the east end of the lake, now shining in the late afternoon light. Almost every yard of its surface shows the scoring and polishing action of a great glacier that enveloped it and swept heavily over its summit, though it is about two thousand feet high above the lake and ten thousand above sea-level. This majestic, ancient ice-flood came from the eastward, as the scoring and crushing of the surface shows. Even below the waters of the lake the rock in some places is still grooved and polished; the lapping of the waves and their disintegrating action have not as yet obliterated even the superficial marks of glaciation. In climbing the steepest polished places I had to take off shoes and stockings. A fine region this for study of glacial action in mountain-making."

I'm almost positive this is the mountain he is speaking of. It's hard to see at this distance, but there was incredibly wavy scoring in the rock face.

"There is another rock, more striking in form than this, standing isolated at the head of the lake, but it is not more than half as high. It is a knob or knot of burnished granite, perhaps about a thousand feet high, apparently as flawless and strong in structure as a wave-worn pebble, and probably owes its existence to the superior resistance it offered to the action of the overflowing ice-flood."

I am 100% positive this is the rock he is referring to at the head of Tenaya Lake. Today you can see people adventurously climbing it:

Yosemite must be one of the best places in the world to study moraine geology. It's really the foundation for everything that makes Yosemite magnificent and unrivaled.