68 



Amador and Calaveras. 



Gravel drift - - 60 feet 



Clays and sands - 40 



Plastic clays - - 50 



White clays - 30 



Cemented gravel and clays - - 45 



Clays, with silicified woods 15 



Auriferous drift - 30 

 Primitive rocks. 



Total, 2tO feet. 



Nevada. 



Gravel drift - - 80 feet. 



Blue and yellow clays - 20 " 



Blue and gray sandy clays, with leaves - 30 " 



Gravel and light clays - 50 " 



Gravel and brown clays - 10 " 



Sands, gravel, and petrifactions - 8 " 



Auriferous drift - 40 " 

 Primitive rocks. 



Total, 238 feet. 



There is much uniformity, it appears, in the general character of the superior 

 coverings of the primitive rocks in the placer ranges, and no little coincidence 

 in the material which makes up the great mass of these beds; as much, at least, 

 as the different sources from which the detrital materials were derived would 

 permit; the modifications that may be present in any of the beds being produced 

 entirely from local circumstances. 



There is one feature, however, that is deserving of notice, and which is strongly 

 marked throughout the State; one of which will enable us to arrive at a much 

 better conclusion relative to the age of these deposits, than any relations which 

 their lithological characters present; this is the close similarity which is manifest 

 among most of the lignites and dycotyledonous leaves found in every portion of 

 this part of the State, as well also as in many parts of the coast mountains. 

 The beds that produce these forms in the mining districts have been placed in 

 the tables as they occur in nature, and we may thus see at a glance theposition 

 which each of these beds hold to each other. 



The peculiarities connected with the distribution of these remains, leads to 

 the conclusion, that a great uniformity of climate, arid other conditions, prevailed 

 for a long period after the disturbance of the older tertiary slates; this is proved 

 from the fact, that comparatively little if any disturbance is manifest during the 

 age in which the drift beds were being deposited. Kotwithstanding these beds 

 are elevated considerably above the sea, they do, in most cases, preserve their 

 conformability with each other, and are unconformable with the slates on which 

 they at many points rest. This may be regarded as one of the evidences of a 

 persistent elevatory action going on through all the periods of the latter, as 

 well as some of the earlier portions of this epoch. It would be a difficult task 

 for the observer to define, with any degree of accuracy, the differences of age 

 between the one part of the state and that of any other, so far as these particu 

 lar deposits are concerned. 



