. 
1887] Sand-Boulders in the Drift in Central Missouri. 919 
_ pebbles of crystalline rocks, from one to four inches in diameter, 
_ ae occasionally found. In a few places there are concretionary. 
; nodules of calcareous matter, similar to those of the loess. 
_ There are some included layers of compact blue clay. In one 
_ Section the remains of a tree were found. 
= 4 The Mechanical Analysis of the Drift, compared with that of 
- the Local Carboniferous Shale.— 
(a) The Drift-clay was found to contain 
Free rounded sand, 2-0.2 mm. in diameter 19.8 
“ “ 0.2-0.1 “ e 9.4 
Clayey sand, 0.1-0.05 “ “ 22.8 
Clay, finer 48.0 
100,00 
Thus we see that the Drift contains not less than fifty per cent. 
of free and generally rounded grains of sand, most of which is 
‘omposed of quartz, with a little that is feldspathic. 
: (4) In the Carboniferous shales there is no distinctly separable 
aaa og T EE 
Stee cease. 
. 
veidrch ea Let Sey teem 
Water, 
. 
Vator ee nr ty TTE ‘es 5-73 
ii 100.40 
:D Sand-Pockets in the Drift-—Wherever cuttings are made in 
of numerous irregular sand-pockets are apt to occur. In 
Of them, however, the sand is mixed with much clay, but 
* The,separation was in a Shéne apparatus. 
