FAUNAL RELATIONSHIPS OF THE MEGANOS GROUP 135 
Knoxville shales (Lower Cretaceous or Upper Jurassic), as seen 
in certain sections of this general area. These sediments probably 
are shallow-water deposits, perhaps laid down in estaurine or 
partially land-locked basins. 
Divisions B and D of the foregoing sections contain much 
biotite. This may be best seen in the sandstones, division D 
forming the ridge on the north side of Deer Valley. In certain 
layers, biotite is very abundant, the flakes being fairly large. Grains 
of feldspar also are present. In fact, the beds may be described 
as arkosic. The basal sandstones, division B, are also micaceous. 
The fauna obtained from these arkosic sandstones indicates a sub- 
tropical temperature; the lithology, taken in connection with the 
evidence for warm subtropical waters, possibly points to arid con- 
ditions on the land. 
In the basal chocolate-colored shales of the Tejon, many 
impressions of leaves, rushes, and fossil wood arefound. ‘These beds 
will undoubtedly yield a large and well-preserved flora. ‘These 
leaf shales were apparently laid down in marginal marine swamps. 
The presence of shells of the genus Corbicula, in a layer of sand- 
stone in the shales, testifies to brackish or fresh-water conditions. 
The most important of the coal beds of this region, and one 
mined throughout most of the area, is found near the top of these 
lower Tejon shales. In the vicinity of Nortonville this bed is 
known as the ‘Black Diamond Vein.” It is reported to have 
a maximum thickness of about four feet. Above this coal seam at 
Nortonville is a sandy, conglomeratic bed varying from 1 to 3 
feet in thickness, which is highly impregnated with limonite. Rush 
and leaf impressions were found also in this layer. The close 
association of this bed with the leaf shales and coal, together with 
the fact that the limonite deposit is limited to a definite layer over 
a considerable area, suggests a primary rather than a secondary 
origin. 
The coarse, cross-bedded, light-colored sandstones immediately 
above the shale may well have been deposited under somewhat 
similar conditions. Two of the important coal-layers, the “Little” 
and ‘‘Clark” veins, mined for many years at Nortonville and 
Somerville, are found in these sandstones. ‘The coal of the Clark 
vein, which is about two and one-half to three feet in thickness, 
