1880.]} 495 [Crosby. 
tion that he has recognized in the last named country the itacol- 
umite, hydromica and other schists and itabarite constituting the 
metamorphic or newer crystalline series of the former, which has been 
connected with the Taconian system. The itacolumite of Guiana 
has also been observed by Schomburgk. 
The limited district in Venezuela known as the Caratal Gold-field 
possesses considerable historical ,interest, since it was, doubtless, 
the fabled El Dorado of the 16th century. It is situated on the 
Yuruari River, the most northern affluent of the Essequibo, and 
about one hundred miles in a direct line south of the Orinoco. The 
principal papers which I have been able to find relating to the geol- 
ogy of this region, are those by R. P. Stevens,! C. LeNeve Foster,? 
Ralph Tate,? and George Atwood.* Besides these, I have the notes 
made by my father, F. W. Crosby, during his residence in that coun- 
try from 1876 to 1878. 
The general line of strike in all this part of Venezuela is east and 
west. The gold mines are reached by the road which runs south- 
easterly from Las Tablas on the Orinoco. This road affords a good 
transverse section of the formations; and, since it is much travelled, 
we find that the contributions to the geology of southern Venezuela 
usually consist chiefly of descriptions of the section from the Orinoco 
to the gold mines. At about one-third of its length from the Orin- 
oco, this line of section crosses the Imataca range of mountains, which 
attains an altitude of about 3,000 feet and forms the water-shed be- 
tween the Orinoco and the Essequibo. . 
The concurrent testimony of nearly every observer from the time 
of Humboldt to the present day is in favor of the view that this sec- _ 
tion consists almost entirely of distinctly stratified crystalline rocks. 
LeNeve Foster begins his descriptions with the statement that “ the 
country between Ciudad Bolivar (on the Orinoco) and Pastora (in the 
Caratal district) consists almost entirely of gneiss, with some mica- 
schist and hornblende schist, and a little granite; and Tate, refer- 
ring to his published section, says it “will suffice to show the regu- 
larity of the bedding, and the somewhat undisturbed condition of 
this series.” 
1 Proc. Phila, Acad. Nat. Sci., 1868, pp. 303-304; and Eng. and Min. Jour., 1869. 
2 Quart. Journ. Geol. Soc., London, xxv., 1869, pp. 336-343. 
3 Quart. Journ. Geol. Soc., London, Xxv., 1869, pp. 343-350. 
4 Quart. Journ. Geol. Soc., London, XXXv, 1879, pp. 582-590. 
