May 15, 1862: Clayton
We were up the mountain in the “nick o’ time,” for it has not been perfectly clear since, and three days after our first ascent the mountain was white with snow, and snow remained on it for three days. We had very cold weather, especially nights.
We continued our work in this region. Although Mount Diablo is the initial point of all surveys for this part of the state, yet, strangely enough, its topography had not been mapped. Nor was the geology at all understood, although it is a most important spot as furnishing a key to many formations of the state, and of great pecuniary interest from the fact that the only coal mines worked to any advantage in the state are on the north side of the mountain and within five miles of the summit.
[This] week we spent in exploring and examining. We climbed the mountain twice, once passing over it to the south and west sides, another time crossing the crest to the east peak, lower by three hundred feet than the main peak, but rocky and almost inaccessible. Its views were the more picturesque. Both days the Sierras were veiled in clouds and the distant view shut out, but all within forty or fifty miles, an area of ten thousand or twelve thousand square miles, was in perfectly plain view.
I cannot detail each day’s work, and were I to do it you would find much sameness in the pictures, for all would be of the same or similar scenes. Yesterday Professor Whitney left for San Francisco to try and raise some money.