Io 
nia, and in the report of Col. Cook’s march from Santa Fe to San 
Diego, published in 1848. 
In the U. S. Exploring Expedition, Vol. X, Geology, Prof. 
James D. Dana gives an account of the Geology of Shasta Mountains, 
also that of San Francisco Bay, with a description of the fossils of 
Astoria, Oregon, many of which are common to the Palaeontology of 
California. 
Only 200 copies of this volume with its Atlas were published and 
it is one of the rarest works of California Geology. 
During the year 1848-49, other expeditions and journals gave a 
few topographical and Geological notes; such as Capt. Johnson’s ex- 
pedition from Santa Fe to San Diego,—and Col Cooke’s march of the 
Mormon Battalion. 
With the discovery of gold in 1848, numerous notices appeared. 
The most important Reports were those by Dr. Tyson: Information in 
Relation to the Geology of California, Washington, 1850. This work 
contains articles on the Geology of the Sierra Nevada Mountains, also 
that of the Coast Range, with the geological structure of the Sacra- 
mento Valley; Gold regions of the Sierra Nevada, 
mines, etc. 
the quicksilver 
This work was republished with an introduction and an index, at 
3altimore, in 1851. 
The most important official document published at this date was 
the report of the Secretary of War, Part 2. 
It contains a topographical memoir, with map of the Sacramento 
Valley, by Lieut. G. H. Derby, pp. 2-16, with Warner’s reconnoissance 
of a route through the Sierra Nevada by the upper Sacramento, pp. 
160-34. 
Exploration of Monte Diablo, ete., by Lieut. Williamson. 
The reports of the Secretary of War, 1850, contain an account of 
boring near Benicia, by Major Vinton, pp. 278-270. 
T. Butler King’s report on California, 1850, gives an account of 
the Geology of the Gold Regions. 
House Doc. No. 17, 31st Congress, 1850, contains a letter from 
Col. Mason. ‘This letter is the first official report on the discovery of 
gold in California. He gives a description of the country along the 
‘American river, and an historical account of the mining regions, also 
a description of the San Jose quicksilver mines. In the same docu- 
