pisci FÉ و‎ a a eS 
APPENDIX. 357 
of tale, and closely resembles the talcose slates of the gold region of the Sierra Nevada and 
Appalachian chain. Exactly similar slates occur in the Carolinas. 
Nos. 31 and 32. Talcose Rocks—Tulare Valley, Aug. 2.—These two specimens are from the 
same locality and differ but slightly. They are magnesian and consist of serpentine and talc 
traversed by quartz veins. The rock is probably metamorphic. 
No. 34. White crystalline Limestone traversed by blue veins—Calaveras Co.—'This is a char- 
acteristic specimen of the white limestone—commonly called cave limestone—which forms an 
extensive belt on the western flank of the Sierra Nevada. It is compact and has an exceedingly 
fine grain, not distinctly crystalline, and is an excellent and durable material for building. It 
is regularly veined with blue in long bands and lines which are sometimes oblique, and closely 
resemble the lines of deposition in sandy strata. The rock, notwithstanding these veins, ap- 
pears to weather very evenly, there being little or no difference in hardness or composition. 
Beautiful slabs of marble can be obtained from this material, as its compact texture is favorable 
to its taking a high polish, and the blue veins give it an interesting appearance. There are 
no indications of fossils or their remains in the specimen, nor were there any found in the rock, 
although an extended surface was examined. This is the limestone in which the great cave of 
Calaveras Co. is formed. It is in all probability a metamorphic rock, but its geological age 
cannot be readily established in the present state of our knowledge of that region. 
No. 38. Quartzite with Talcose Slate—Four Creeks.—This specimen is nearly all quartz, but 
it appears in contorted layers like a slate. It is, in fact, interstratified to a slight degree with 
softer material, probably talcose slate, in which it is found. The weathered surface shows a 
succession of regular layers; but the cross-fracture shows a compact, homogeneous mass of 
quartz. 
No. 39. Picrolite—Four Creeks, Aug. 3.—This specimen is a green, fibrous, or columnar 
mass, resembling the picrolite of the southern counties of Pennsylvania. The mass does not 
separate into fine silky tibres like asbestos, but is hard and compact. It has an oil-green color 
like that of precious serpentine. ' The direction of the fibres is oblique to the side of the 
Specimen. 
No. 40. Metamorphic [?]— Four Creeks, August 2.—This rock is dark-green and compact, and 
resembles a greenstone or trap. It, however, has a laminated structure or slaty stratification, 
which, with its association, causes me to refer it to the metamorphic rocks, although from 
the specimen alone I should be inclined to consider it eruptive. I am more inclined to this 
view, as specimen No. 63, which I marked at the locality as eruptive, has very similar mineral 
characters, 
Nos. 42 and 43. Quartzite—Four Creeks.— These two specimens have a general and, indeed, 
close resemblance. No. 43 exhibits the granular structure of sandstone very clearly, but it is 
perfectly hard and compact, all the grains being thoroughly cemented together. No. 42 is still 
more thoroughly metamorphosed, and the grains are not so distinctly seen. 
No. 46. Slate containing Andalusite—Crossing of the ۵ River.—This slate was taken 
from the strata of sandstone and conglomerate on the banks of the Chowhillas, in which it is 
very abundant. It is dark-bluish gray—the ordinary “ slate-color ’’—and is charged with small 
crystals of andalusite or macie. The quantity of the slate in these strata shows that it must 
exist in very considerable quantities on the slope of the Sierra Nevada, in that region. 
No. 86. Blue sandstone— Yerba Buena Island, and Francisco Bay.—This is a fair specimen of 
the compact blue sandstone of San Francisco and its vicinity, which is so much used for build- 
