294 BED CONTAINING FOSSIL SHELLS 
and, on striking the nucleus a slight blow with a hammer, 
one or two more layers are broken off. It is owing to this 
facility of decomposition that the annual rains carry down 
such vast quantities of alluvial soil from its surface, which 
is, moreover, always strewed with an abundance of nuclei, 
in various stages of decomposition. It is owing to the dif- 
ficulty with which the roots of trees penetrate this rock, that 
they are so rare on its surface, and never grow to any size. 
Yet this circumstance does not prevent the Andropogon 
coniortum and nardus from growing in the most luxuriant 
manner, which sufficiently proves the fertility of the soil. 
On ascending from the Taptee (in April 1823), I observed 
in a nullah Si group of basaltic columns, one of which was 
two feet in diameter, and six-sided. When near the summit 
of the flat table-land of Jillar, I entered a pass, formed on 
one side by a perpendicular section of the rock from 25 to 30 
feet, and on the other by a rapid descent of 40 or 50. The 
lower part of the section, as well as the pathway, is com- 
posed of the wacke or indurated clay of the kind before 
mentioned, of about 10 feet in thickness. Lying on it is a 
stratum of earthy clay, of different degrees of induration 
and purity, 20 yards in length, and about 2 feet in thick- 
ness, containing great numbers of entire and broken shells. 
This possesses all the characters of a stratum, since the hori- 
zontal fissures are parallel, and are prolonged, with a few 
interruptions, through the whole extent. The accompany- 
ing sketch (PlateVIII. bottom) \n\\ serve to give a tolerably 
correct idea of the mode in which the stratum appears to 
overlie the lower rock, and to have been depressed by that 
which is superincumbent. The upper rock consists of 
about 15 feet in thickness of the nodular basalt or wacke, 
the nuclei being of all sizes. The vertical fissures which 
are so remarkable in trap-rocks, are prolonged from both 
the upper and lower rocks into the shelly stratum, although 
