J. LeConte—Ancient Glaciers of the Sierras. 329 
current careless of domes. The period of this ice-sheet, of 
course, preceded that of the separate glaciers which I am now 
tracing. 
Another point of some interest which I observed here was 
the existence, everywhere in the lower part of Little Yosemite, 
even down to the Nevada falls, of erratics of a peculiar granite 
composed of very large and very perfect crystals of feldspar, 
cemented together by a paste of finer granite. These crystals, 
which were often four or five inches in length, stood out on the 
weathered surfaces so that the boulders looked like masses of 
coarse conglomerate or breccia. We traced these boulders up 
Feldspar valley (so-called from this remarkable granite) to 
their parent rock, viz: Cathedral peak and other peaks and 
comb-like ridges in that vicinity. 
Cathedral Peak (11,000 feet high) is the most conspicuous of 
a cluster of sharp spire-like peaks and comb-like ridges in this 
Vicinity; spires and ridges so steep and sharp that it seems dif- 
ficult to understand how they can remain standing from year to 
year. These seem all to be formed of the peculiar granite spoken 
of From the immense masses of snow which once accumu- 
lated amongst these peaks, and which still linger there in 
small quantities in sheltered spots, in glacial times there issued 
a glacier which passed down Feldspar valley and, joining the 
Little Yosemite glacier, poured its icy flood over the Nevada 
and Vernal falls into the Yosemite valley 
granite, glaciat 
Surface had the a pearance of polished brecciated marble. 
glacier. It has been polished on every side and over the top 
until it is rounded like the carapace of a tortoise. 
he Tenaya cafion between Lake Tenaya and Mirror lake 
[have not examined. Just below Mirror lake there is a pile 
of boulders across the cafion. This I believe to be a moraine. 
