SOLIMOES AND JAVARY RIVERS, IN BRAZIL. 81 
ft. in. 
“Surface deposit... 10 O Red and white clay. 
5 0 Blue clay, full of fossils. 
13 0 { Blue clay, with an occasional shell too badly 
| preserved to be removed. 
Lignite. For a few inches above and below 
9 | this the clay is filled with vegetable re- 
mains. 
15 0 { Blue clay. In the middle is a band 8 feet in 
thickness containing shells. 
Talus disguising rest of section.” 
The chief differences in the two are, that in the place of the 
nodular calcareous bed of the upper Canama section, the Pebas sec- 
tion has a layer of lignite: while the arrangement of the fossils 
appears to be somewhat different. From my lower Canama section 
it would appear as if the upper bed of lignite corresponded in posi- 
tion with the nodular caleareous bed—in fact, that one passed hori- 
zontally into the other. It appears to me that the Pebas 13- and 
15-feet beds of blue clay correspond exactly to, or are the same as, 
the two Canama 14-feet beds of blue clay. Thus it will be seen 
- that though the sections vary on the Javary in short distances, still 
there is a remarkable similarity between one section there and one 
at Pebas. 
One cannot fail to be struck with the great extent of these beds, 
occupying a tract of country, as far as at present known, of 300 
niles in length by 50 miles in breadth, and containing, curiously 
enough, associated fresh- and brackish-water shells, as well as with 
their position at so great a distance from the Atlantic ocean. At 
the time of their deposition the physical features of the north-eastern 
portion of South America must have been vastly different from what 
they are at the present day. ‘The sea then reached far inland, pro- 
bably to 1500 miles west of its present shore-line, and covered the 
country which is now the valley of the Amazon. Instances of false- 
bedding, showing the action of the strong currents, being nowhere 
observable in the beds of this deposit which have been examined, 
it is probable that they were formed in comparatively still water, 
into which flowed numerous streams bearing much vegetable matter. 
I think we may infer that they are almost the highest beds of a 
series which has been deposited under similar conditions to delta- 
beds of the present day. No speculation of this sort can as yet take 
a definite form, but all must remain visionary until further data have 
been gathered bearing upon the extent, nature, and thickness of this 
deposit where it occurs in other portions of the same region. Then 
we may arrive at the true explanation of its deposition, and find 
out whether it is an old delta as supposed, or otherwise, as well as 
whence came the rivers which contributed to its formation. 
It is with a view to assist in the elucidation of these problems 
that I have here recorded my observations on the structure and ex- 
tent of these interesting Tertiary beds, where I have met with 
them. 
Q.J.G.8. No. 137. é 
