W. P. Blake on the Grooving and Polishing of Rocks. 179 
Wherever I turned my eyes—on the horizontal tables of rock, 
or on the vertical faces turned to the wind—the effects of the sand 
were visible: there was not a point untouched, the grains had en- 
graved their track on every stone. Even quartz was cut away 
and polished ; garnets and tourmaline were also cut, and left with 
polished surfaces. Masses of limestone looked ds if they had 
been partly dissolved, and resembled specimens of rock-salt that 
have been allowed to deliquesce in moist air. These minerals 
Were unequally abraded, and in the order of their hardness ; the 
Wear upon the feldspar of the granite being the most rapid, and 
the garnets being affected least. Whenever a garnet or a lump 
of quartz was imbedded in compact feldspar and favorably pre- 
sented to the action of the sand, the feldspar was cut away aroun 
the hard mineral, which was thus left standing in relief above 
the general surface. A portion however, of the feldspar, on the 
lee side of the garnets, being protected from the action o 
sand by the superior hardness of the gem, also stood out in relief, 
forming an elevated string, osar-like, under their lee. 
When the surface acted on, was vertical and charged with 
sarnets, a very peculiar result was produced ; the garnets were 
left standing in relief, mounted on the end of a long pedicle of 
gton about San Francisco, where they are all bent from the per- 
Pendicular in one direction, or in some places lie trailed along the 
ground. All these little fingers of stone pointed westward, in the 
direction of the valley of the Pass, to which the wind conforms. 
€ experienced this wind before reaching the point of rocks and 
