Bye A. P. COLEMAN 
typical outcrops in the field. Through his courtesy and kindness 
I had an admirable introduction to the Paleozoic bowlder clays of 
Brazil. f 
TILLITES IN THE STATE OF S O PAULO 
In tropical Brazil, with its moist, hot climate, weathering goes 
to great depths, and even in the southern parts of the country, 
where the climate is warm temperate, the products of decay mantle 
most of the surface; so that fresh outcrops of rock are seldom to be 
found under natural conditions. On this account the most satis- 
factory points for geological work are cuttings along the railways 
or depressions where roads ascend hills and the wheels of vehicles 
have worn their way downward. To an observer fresh from parts 
of North America where the Pleistocene glaciation has left clean 
surfaces of almost unchanged rock this is most disconcerting, and 
it takes a little time to adjust one’s self to the new conditions. The 
working out of field relations is greatly hampered by the products of 
weathering, which usually hide even the weathered rock and may — 
accumulate to considerable depths on slopes and in valleys. 
Under Dr. Pacheca’s guidance a number of railway and road 
sections were visited to the north of the city of Sao Paulo, the first 
region being near the thriving city of Campinas. In railway 
cuttings two or three kilometers from the city, tillite rests upon 
gneiss, probably of Archean age, two mounds of the gneiss rising 
with rounded forms suggesting roches moutonnées; but unfortu- 
nately weathering has gone so far at the contact as to destroy any 
smoothed or striated surface that may have existed in the beginning. 
According to Dr. Pacheca this is almost the only example known in 
Brazil of tillite resting on what must have been a scoured surface 
of solid rock. 
The tillite is weathered and scarcely harder than certain 
Pleistocene tills, though its yellow or red or chocolate-brown color 
is unlike the customary bluish gray of North American bowlder 
clay. Striated stones were not found here, though the general 
appearance of the rock was that of tillite, some of the more resistant 
stones inclosed‘in it, such as quartzite and granite, still showing 
subangular forms and smoothed surfaces. Overlying the tillite 
are shaly or sandy beds, distinctly stratified and including some- 
