Ixviii REPORT OF THE STATE GEOLOGIST. 



coal measure fossils. This is capped by one thousand feet of white 

 limestone with many fossils, some of which are the same as those 

 found in our upper coal measures, but numbers of others have been 

 described as belonging to the period which follows. Lithologically, 

 we have here a base corresponding to our Bend Series, followed by 

 a great thickness of sandstone and bands of limestone covering the 

 period of our entire coal series, showing that at this region the sea 

 bottom remained at a more uniform depth. 



The upper limestone corresponds in its lower part to the Coleman- 

 Albany Beds, lithologically, and also in the fossil remains. The Car- 

 boniferous limestone of the Eagle and Diabolo mountains, so far as 

 they have been determined, also seem to belong to this horizon. Coal 

 occurs in this district, but its extent is unknown, and where exam- 

 ined does not promise much. 



The rocks, therefore, which comprise the strata of the Carboniferous 

 System show by their composition and character a sea of varying 

 depth, with land conditions to the east and south. The life was very 

 abundant, great numbers of fossil shells being found throughout the 

 different series of beds; remains of coal plants are plentiful, and some 

 fragments of vertebrates have also been found. These beds differ 

 from the deposits of the Tertiary, in their continuity especially. In 

 the latter formation a bed of sand alters in a short distance to a bed 

 of clay, and the lignitic coals exist in lens-shaped masses, while in 

 the Carboniferous all these are more persistent, and while a seam of 

 coal may vary in thickness it very rarely is wanting altogether, un- 

 less from erosion. 



In addition to the great value of the beds of this system to our 

 State for the coal they contain, they are equally valuable in their 

 other economic aspects. They contain large deposits of admirable 

 building stone, some of which is altered into a compact limestone or 

 semi-marble and takes a very fine polish. Even the coarser kinds 

 make good dimension stone, and are used all through the district in 

 which they occur. The sandstones are also used to some extent. In 

 connection with the coal we find large deposits of very valuable fire- 

 clay which must when properly developed be of great value. Clays 

 for brick and pottery-making exist also, and sands for mortar are 

 abundant. 



The soils of the Carboniferous are varied as the alternating strata 



