tjghan.] SECTIONS IN VICINITY OP SAN CARLOS. 77 
Eroclastic material. The basalt occurs at about the center of the 
sction, and apparently is intrusive into the bed immediately over- 
ing it. The reasons for this conclusion are given in the discussion 
: No. 11' of the preceding section. 
In the sediments interbedded with the lavas and pyroclastics no 
>ssils were found, and we could not determine the precise age of the 
iries. For these interbedded lavas, pyroclastics, and sediments 
te name Vieja series is proposed, from the Vieja Mountains, where 
Ley are well exposed and where they were studied. 
SECTIONS IN THE VICINITY OF SAN CARLOS. 
ction of the Vieja Mountains from the San Carlos arroyo, 1 mile below San Carlos, to 
the top of the mountain east of the town. 
(PI. VIII; PI. XI, fig. 2.) 
Feet. 
. Rim rock, a greenish-yellow rock, containing large phenocrysts of anor- 
thoclase feldspar, determined by Dr. Lord to be quartz-pan tellerite.. 400-000 
. Variegated sandstones and clays, and probably rhyolite breccias 500 
(It was not possible to examine this part of the section carefully, so 
the notes are very meager.) 
. Grayish and purplish clays, etc. , approximately 500 
. Yellow clays, or soft yellow sandstone, with occasional carbonaceous 
seams „ 150 
. Carbonaceous seam 20 
. Yellow or purplish clays, with ledges of soft yellow sandstone and 
occasional carbonaceous seams 250 
. Coarse, soft, yellow, cross-bedded sandstone 25 
. Yellow clay, with two or three carbonaceous seams 20 
. Coarse, soft, yellow, laminated sandstone in ledges 30 
. Yellow clay, carbonaceous at base 6 
. Coal If 
. Impure coal 3 
. Carbonaceous shale 1 
. Purple clays 4 
. Coal 1£ 
. Purplish clays 4 
. Soft yellow sandstone and argillaceous sandstone 110 
. Yellow or brown sandstone; 40 feet above base limestone concretions; 
a few poor fossils, mostly Exogyra fragments 90 
. Ledge of brown sandstone, containing well-preserved specimens of a 
large Inoceramus (/. oblongus Meek) in great abundance 4 or 5 
. Laminated brown or yellowish fossiliferous sandstone; about 20 feet 
below the top there is an indurated ledge containing many oysters.. 250 
. 'Clay, with calcareous concretions which contain many well-preserved 
fossils 40 
. Thinly laminated clays weathering yellowish, capped by soft, yellow, 
laminated sandstone 20 
The total thickness examined, a little less than 2, 700 
