tO The American Geologist, January, 1896 
;!. The post-Lafayette period of erosion exceeded the posl 
( ol 11 labia by al least the ratio of live to one. 
4. The Columbia deposits in the Spring River valley indi- 
cate a gradual subsidence of the region, increased precipita- 
tion, decrease in average annual temperature, and ;i muddy 
condition of the waters. 
."». Apparently the movements of the earth's surface were 
here greater in amount than farther east in the centra] por- 
tions of tlie Ozark region. They probably increased in inten- 
sity from some area in Arkansas northwestward to some area 
in the tipper Missouri valley: and the Spring River region 
was also doubtless somewhat effected by movements in the 
Rocky Mountain region. 
What has been here said in regard to the phenomena in the 
Spring River valley in Cherokee county. Kansas, applies with 
equal force to adjacent portions of Missouri and the Indian 
Territory. The Columbia deposits are well developed along 
Shoal creek and along Spring river and its main tributaries 
in Missouri. The red gravelly clay, which I consider the 
equivalent of the Lafayette formation, appears also along the 
streams in southwestern Missouri, and indeed in the valleys 
of the entire Ozark region; and Mr. Winslow is, I believe, 
correct in referring its deposition to Tertiary time. 
THE TIMEPIECE OF GEOLOGY. 
By E. W. Claypole, Akron, Ohio. 
In the early days of geology superposition was the only 
test of age. As soon as (dear ideas regarding the structure 
of the stratified rocks were attained and their general rela- 
tions to the unstratified masses became known, it was an 
obvious deduction from this knowledge that the lower strata 
were the oldest and that the overlying ones had been laid 
down consecutively upon them. The distinction into Primary, 
Secondary and Tertiary soon arose, and of this early nomen- 
clature some traces still survive. But the work of William 
Smith, the father of English geology, awakened a suspicion 
that these rocks contained in themselves evidence that might 
he used to determine their dates. This supposition rapidly 
became a certainty as collections increased and as their speci- 
mens were more and more closely studied. Paleontology was 
