SOLIMOES AND JAVARY RIVERS, IN BRAZIL. ia 
Amazon valley, similar to the loess of the Rhine, is of exceeding 
interest, cliff-sections of it, ranging from 10 to 300 feet in height, 
being exposed in many places on the banks of the great river and 
its tributaries, where, in their windings through their present 
alluvial plains, they pass at intervals by its edges. It lies uncon- 
formably upon the Tertiary clays; for, on the Javary, the white 
and red sands are seen forming the upper portions of some of the 
cliff-sections, resting on what are undoubtedly denuded surfaces of 
the fossiliferous beds. Unfortunately, in every instance, the actual 
junction of the two is obscured by talus and landslips. As every 
geologist who has worked in the tropics must be aware, cliff-sections 
are invariably unsatisfactory in their greater portions, owing to 
landslips caused by atmospheric agencies, and to the dense masses 
of vegetation which cover them with an impenetrable mask when 
their faces incline in a slight degree from the perpendicular. Again, 
another difficulty presents itself—the sections along a river bordered 
by recent alluvium are never continuous, long intervals of low mud 
shores intervening between each exposure, and forming puzzling 
breaks in their continuity, very trying to one who is endeavouring 
to trace out the sequence of a set of beds. 
Professor Hartt, in the paper before referred to, speaking of some 
sections examined and described for him by a Mr. Steere, remarks as 
follows :—‘‘ In examining the above sections we find the surface- 
bed always composed of variegated clays, with more or less sand, 
which, according to Mr. Steere, were deposited on the much denuded 
surface of the lower fossiliferous beds, the last being clearly Ter- 
tiary.” Here, then, we have further evidence that there is no 
relation between the two deposits, the upper being, as I before 
stated, a river-deposit, and the lower a brackish-water formation. 
Previous to the time of my visiting the country, the Tertiary 
deposit had been traced from Loreto, in Peru, down the Amazon to 
a short distance below Tabatinga, in Brazil. The most easterly 
spot at which I met with it on the Solimdes, or Upper Amazon, 
was in a cliff-section two miles below St. Paulo, a town situated on 
the southern bank of the river, at a distance of 1350 miles from its 
mouth, measured in a straight line, and 150 miles below Tabatinga. 
Following the bends of the river, the distance is 1922 miles. 
Although there were no fossils to be seen, yet, from its similarity to 
the fossiliferous beds on the Javary, I feel confident that it is part 
of the same formation. 
A detailed section of it gives the following horizontal layers :— 
Soll Cencooseaoec Yellowish loam. 
(10 feet. Greyish-blue clay. 
5 ,, Dull purplish clay. 
3 ,, Dark clay, impregnated with vegetable matter. 
1 foot. Impure lignite. 
Tertiary ...... 10 feet. Greenish-blue clay. 
1 foot. Impure lignite. 
20 feet. Greenish-blue clay. 
10 ,,  Bluish arenaceous clay, containing calcareous no- 
\ dules. 
River. 
