176 
PHYSICAL HISTORY OF THE 
they exhibit in patches an extraordinary vari¬ 
ety of beautiful colors, — pink, orange, crim¬ 
son, yellow, gray, blue, and also black and 
white. The Indians are very skilful in pre¬ 
paring paints from these colored clays, with 
which they ornament their pottery, and the 
bowls of various shapes and sizes made from 
the fruit of the Cuieira-tree. These clay de¬ 
posits assume occasionally a peculiar appear¬ 
ance, and one which might mislead the ob¬ 
server as to their true nature. When their 
v 
surface has been long exposed to the action of 
the atmosphere and to the heat of the burning 
sun, they look so much like clay slates of the 
oldest geological epochs, that, at first sight, I 
took them for primary slates, my attention 
being attracted to them by a regular cleavage 
as distinct as that of the most ancient clay 
slates. And yet at Tonantins, on the banks 
of the Solimoens, in a locality where their 
exposed surfaces had this primordial appear¬ 
ance, I found in these very beds a considerable 
amount of well-preserved leaves, the character 
of which proves their recent origin. These 
leaves do not even indicate as ancient a period 
as the Tertiaries, but resemble so closely the 
