CLIMATES OF GEOLOGIC TIME—SCHUCHERT. 305 
times, while the interbedded red strata of the Proterozoic tillites 
seem to point to the same variability. It is this decided temperature 
Polat below) sedboho loll bitihaic | aor bea 
Liked ie 
ne me santas = 
CACCE eet 
a 
CT 
aD aay 
Jurassic 
rmic¢ || Triassic 
Pe’ 
ic 
auea ; 
-[Asuuag 
Carbon 
ISSUW 
JIM] 
=| = 
eE 
iP 
= 
Times of mountain making 
ia 
Lower 
Carbonic 
Juric | Devomiec 
aquoaag 
LS 
DUNS 
ca 
Positive (land) strand line curve 
waa ce 
eo |e WA EIN 
1 
Si 
ian 
Ordovicic 
Fig. 4.—Chart of geological climates—Paleometeorology. 
Proterozoic 
pical temperature 
Frigid temperature 
Geologic time | 
Geologic time 
Tro 
fluctuation during the glacial periods that is so very difficult to 
explain. 
In addition to the well-known Pleistocene and Permic glaciation, 
_ there is rapidly accumulating a great deal of evidence to the effect 
73176°—sM 191420 
