230 MR. SPRUCE'S BOTANICAL EXCURSION 
Tn ascending the Aripecuri, the first rock that appears is apparently 
the same coarse dark-coloured sandstone seen at Obidos and Para; 
it dips at a small angle to S.S.E. A little before reaching the 
cachoeiras, crops out from beneath this a soft red and yellow sand- 
stone,* which in its upper strata becomes slaty. Then at the cachoeiras 
we have real slate rock, of a purple or purplish-grey colour, in beds, 
also dipping to S.S.E., at an angle of 10°. It cleaves principally in 
two directions (besides that of the strata), the lines indicating which 
run from E.S.E. to W.N.W., and from N.E. to S.W. There are also 
other lines less regular and distinct, one of which runs N.W. by 
W.3W. From below the slate emerges the granite, which is very 
cotra grained, and seems to contain all the usual constituents of that 
rock, I send specimens of all these rocks. 
The forest near the cachoeiras is exceedingly dense and moist; it is 
consequently always cool, even at midday, and our Tapuyas, who 
were very sensitive to changes of temperature, complained of being 
dreadfully cold. It contained many magnificent trees, among which 
the most conspicuous were the Castanheira, the Sapucdya, and two or 
three other Lecythidee. The whole district of the Trombétas and 
Aripecurü abounds in Castanhas, and, in the season for collecting 
them, which is the middle of winter, troops of Indians ascend these 
rivers. Other trees worthy of note are the Uapwí, appearing like 
clustered gothic pillars, the Z/aba, the Caraipé, &c. The Ttaüba we 
had seen in plenty also near the Lago de Quiriquiry, but neither there 
nor here did we meet with any which were sufficiently slender to admit 
. Of their being ascended or eut down. It is a noble and clean-growiug 
tree, with rather shaly bark, which, having besides a slight tinge of red, 
: gives the trunk the appearance of that of the Scotch fir, though the 
leaves proclaim it to belong to a very different family. Near Santarem 
it is becoming rather scarce, but I am now waiting in hopes of shortly 
procuring it in flower. 
The Palms which I noticed were the Inajá, Jauari, Murumurié, Assat, 
Marajá, Ubim, Ounhat, a Desmoncus, and some small Bactrides. All 
these, with the exception of the Jawarí and Ounhat, 1 had previously 
* When this rock is broken, spherical nodules of a purple colour and the size of 
apples frequently tura out. They consist of a stony crust, filled with earth of the 
. same colour. 1 send one. 
