92 
HYDROGRAPHIC REPORTS. 
The following extracts from the Report of Mr. John McLeod 
Murphy, TJ. S. Navy, contain the results of a reconnaissance 
of the Bio del Gorte, and a survey of the Uspanapa. 
Leaving the Hacienda of Tarifa, I took the road for San Mi- 
guel Chimalapa, lying in an easterly direction, and crossed the 
Plains of " Las Tablas," which extend to the base of the Cerro 
Convento, a distance of one and a half Mexican leagues. These 
plains, consisting of black loam and variegated marl resting 
upon sandstone, are covered with long grass, and present a 
broad extent of excellent grazing land. They are, however, 
traversed in an east and west direction by the Arroyo Paso Par- 
tida, a tributary of the Chichihua. This arroyo for a greater 
part of the year is dry, but in the rainy months — July, August, 
and September — it overflows, and covers the entire plains on 
the south side to the depth of three and four inches : later it 
serves as a natural drain for the land. 
Entering the Paso Partida, the small hillocks clustering round 
the bases of the adjoining mountains are covered with oaks and 
pines : and further beyond, the road lies through a magnificent 
forest of the latter, extending for more than a league over the 
entire pass, which consists of compact limestone and clay slate, 
mingled with fragments of diorite. The pine-trees here are 
similar in all respects to those of the southern portions of the 
United States, and vary in diameter from one and a half to 
three feet. Of their importance and value, either for timber 
or as yielding tar, resin, and turpentine, there can be little 
question, especially when their proximity to the proposed rail- 
road, and the facility of transportation over a level plain is con- 
sidered. East of the pass, and to the right of the Convento 
Grande, the road winds through a valley covered with every 
variety of trees and plants ; among which are the mahogany 
(often four feet in diameter), the ocosote (yielding a fragrant oil), 
the guayacan, the guaco, the cuapinol, the tamarind, &c. Sub- 
sequently the road passes around, and over a number of moder- 
