Transcription:
on letterhead: Pen Sentinel Hotel, A. C. BLACK, Proprietor. Yo Semite Valley, April 20 1872 Dear Le Conte, Yours of Jan
19th was duly re'cd I am glad to know that you hope to gather your thoughts concerning mountains into definite form that you
will certainly come here glean facts in this magnificent region. Sometime last fall I sent you a letter made up of facts,
hints, guesses concerning mtn' structure wh you may not have rec'd. At least I have not had any answer to it. Therefore I
will repeat a portion wh I hope may interest you drawing Cross Section of West Slope of Sierras through Merced basin
with Slates reconstructed upon the divided? granite up to the present level of Summit Slates those of foot of the ranges