Cretaceous Clays in Middle Georgia. — Ladd. 247 
RESULTS OF PHYSICAL TESTS. 
Water 
absorption 
Shrinkage 
on drying 
Shrinkage 
on burning 
Fusibility 
Tensile 
Strength, 
dried, per 
sq. inch. 
25 lbs. 
Specific 
Gravity 
112% 
8% 
3>2to4% 
Seger 
cone No. 
36-* 
1.76 
80% 
4>2% 
4% 
Seger 
cone No. 
36- 
Seger 
cone No. 
35- 
10 lbs. 
1. 91 
.100% 
8% 
2% 
24 lbs. 
1.72 
(h 
98% 
18 to 20% 
2% 
iioo« C. 
304 lbs. 
I .90 
3^ 
200% 
25% 
6% 
1330'^ C. 
213 lbs. 
0.90 
An average sample taken from one of the workable beds 
is white in color, when dry, and very fine grained. Muscovite 
scales can only be detected by use of the lens. Grains of 
quartz are extremely rare and only to be seen under the micro- 
scope with a high power. The microscope shows it to contain 
but little muscovite and to be one of the purest clays of the 
fall line belt. It readily absorbs water and becomes plastic. 
Miller Clay. The Miller clay occurs pn the property of L. 
F. Miller, which is situated about 3 miles south of Gordon. 
The thickest bed seen in Georgia of the white Cretaceous clay 
is here exposed. A section along the slope of the hill shows 
at its base thirty feet of the white Cretaceous clay unconform- 
ably overlaid by one hundred and twenty feet of massive Terti- 
ary clays which in turn are unconformably overlaid b)- orange 
and vermilion sands probably of Lafayette age. 
The clay examined and analyzed is remarkable for the pres- 
ence of an abundance of pear-shaped areas, averaging three- 
fourths of an inch in greatest diameter, and consisting appar- 
ently of a finer grained, darker colored clay material. This 
clay is also noteworthy on account of its property of hardening 
on exposure to the atmosphere. Often for several feet from 
the surface it is exceedingly hard and tough, being difficult to 
