W. M. Fontaine—Mesozoie Strata of Virginia. 235 
k 
_ The last of the surface deposits on the Azoic which are of 
importance are certain clays which are the most widely diffused 
of all. Thus we find them over the surface of the Azoic 
everywhere, to the west of the Petersburg Belt as far as the 
Catoctin and the Blue Ridge. They are not continuous but 
belt, or that the Azoic drift in that quarter extends far west- 
ward of the eastern edge of the Azoic, as I have not made any 
extended examination there, but so far as I have examined, the 
condition of the surface is much as it is west of the Petersburg 
elt. These clays are the only transported matter that I ob- 
served in the southern part of the State, in Pittsylvania County. 
Here they occur in the same way as in the northern district, 
now being described. as 
These clays are nearly always blood-red in color and rich in 
lime. They form a highly fertile subsoil, no matter on what 
sort of rock they may rest. They lie on all kinds of rocks, and 
are entirely independent of them. We find them on the gray 
grits of the Mesozoic; on the granite, with its surface decom- 
posed to a white kaolinic grit, which shows the utmost possible 
contrast with the clays; or on mica-schists, etc. There is no 
rock east of the Blue Ridge rich enough in lime to yield these 
clays, except the epidotic schists, and hornblendic rocks which 
abound so between the Blue Ridge and the Catoctin. Theclays 
contain decomposed fragments which resemble these strata, and 
when we can follow them, as we do up to these schists, we may 
conclude without hesitation that such is their origin. Hence 
they must have been transported in many cases, fifty or sixty 
miles. This however is not strange when we see that the Pots- 
dam and other rocks from west of the Blue Ridge, must have 
