•>-4 IlnAllnrictlit (I'ln/tK/tst . Ni.vfiiilMT, isin 
<liti(iMs will |»i('\:iil in ;i(lj:ici'iit seas, and :i dittrnMit cIjims of or- 
>r;uii.suis will iiiliiiltit their waters. When the land has disap- 
peared altogether. tli»' walei's will Ite clear and well siiitt'd to the 
•rrowth of lime-secret iii<i' animals. Thus there will Ik' a cycle of 
liviiio foi'ins corresjjondiiiii to each cycU' of sedinieiitatioii. hut 
owiiiii' 1" the loiiii' (hiration of those sedinicntai'V cvcles. ami the 
mutability of animal types, the cycles of life will rar»'ly if 
ever repeat themselves in consecutive cycles of sedimenta- 
tion. 
In conclusion we may say that tiii' iit'ueral fact of cycli's of 
sedimentation is well established. They arc best ex|)lain<'d as 
resulting from the secular elexations and dilteiciitial rates of 
erosion of land areas. The elevations must have been j)eri()dic. 
This periodicity was due to other secular pheuomi'na of a mon' 
general and fundamenttd character. Tlw followin^i,- are the most 
important of those phenomena: 1st. The secular cooling and con- 
seijueut contraction of the earth's crust. 2d. Thi' alternate^ 
occurrence of periods of refrigeration at the northern and south- 
ern hemispheres diu' to astronomical events. '.'a\. The generation 
and expansion of gases and vapors at the bottom of the seas 
I'csulting in ci-ustal disturbances. By the indcfx'iuUMil or united 
activities of these several forct's there have resulted jM'riods of 
profound antl universal disturbances occurring at widely removed 
intervals of time. While those intervals have been marked by a 
|)revailiug (luietude. yet thei'(> was a continuous succession of 
minor disturb;inces relatecl in some complex way to those same 
general forces, which lunc given rise to cycles of sedinu'utation. 
Jnlfi .'S. IS'.n. 
KDITOJMAJ. U()M\lliL\^l\ 
The study of geology is no light and easy task. lloltcrt .Mal- 
let once wrote that to be a geologist a num must lirst be a ciiem- 
ist. then a physicist, and lastly a mathematician. (leology can- 
not be mastered t)y reading the literature of the science, iuti'i'cst- 
iug and important as it is. Nor can tlu' alternate loading and 
discharging of a few pages of a school or college text book make 
a geologist. (Icologus nascitur. non lit. is a true parody of the 
oriirinal. No man can lie a u'eolo<>ist unless the stutf is in him. 
