584 G. ATTWOOD ON SOUTH-AMERICAN GEOLOGY. 
The rock may be called a “ highly felspathic granite.” Leaving 
the sabanah, which extends about six miles in width, the tropical 
forest commences and continues until the town of Upata is reached. 
About two miles beyond the commencement of the forest a beautiful 
granitoid rock, full of garnets, takes the place of the felspathic gra- 
nite. It contains 48°50 per cent. silica, and 11-50 iron=peroxide 
14:95 per cent. This rock is found for about 4 miles, and also near 
a ranch called San Juan. At the crossing of the Upata river rocks 
of a schistose micaceous character are met with. They are of a 
white colour with dark specks, and consist of quartz, felspar, and 
mica. These rocks are then followed to Las Corales (552 feet above 
sea-level, seo Pl. XX XIII.), the road still winding its way through 
the forest. 
At Las Corales a change in the rock is found, and highly felspathic 
eranite again comes in. No change of decided character in the rock 
is found until the village of Alta Gracita is reached. The rock on the 
summit of the mountain-pass (of the mountain called Moyori) is 
found to contain much less mica than at the base of the mountain ; 
but as the rock on the pass is highly weathered, no great attention 
was paid to the fact. The last-named pass is the highest point in 
elévation but one found in my section, being 1298 feet above sea- 
level. 
About a quarter of a mile 8.E. of Alta Gracita large masses of 
ferruginous quartzite are met with, and in places they are found to 
be stratified. Hematite and magnetic iron-ores of great purity 
occupy more than two miles in length. In places pyrrhotite is met 
with ; the bronze-yellow and copper-red colour on the fresh fracture 
of the mineral is sufficient to distinguish between it and pyrite 
without the aid of a magnet. 
Upon approaching the old Spanish town called Upata, situated on 
the Upata river (a stream that finds its way into the Orioco), and 
1165 feet above sea-level, a change of rock occurs. The rock is a 
crystalline one and consists of rather irregularly formed grains of a 
felspar and a greenish mincral. Prof. Bonney pronounces it to be 
igneous, and calls it a quartz diorite. 
Continuing the journey in a south-easterly direction, the quartz 
diorite extends about eight miles, when a ferruginous quartzite 
comes in, and extends for nearly ten miles. 
Some stones taken as an average sample were found to contain, 
by analysis, silica 50 per cent., iron 35-00 per cent.=peroxide 45°50 
per cent. For several miles these deposits of hematite were found 
stratified, having a 8.H. strike and dipping 8.W. at an angle of 70°. 
Large masses of pure magnetic iron-ore were also found; anda large 
area comprising from seven to eight miles was found composed of 
the mixed iron-ores. 
On approaching the base of the mountain called Mano Piedra, the 
quartzite contains but a small quantity of iron, and finally gives 
way to a belt of about half a mile in width of quartz breccia made 
up of very coarse angular fragments. The breccia is then replaced 
by a beautiful granite consisting of pink quartz, mica, and felspar. 
