194 on THE TorociKAPiir and geology 



rocks are probably dykes extending- from it. I crossed the country behind, or to the 

 north of it to Maniel from the head of the Ni^na, a distance by the ronte followed of 

 abont forty miles, althongh the entire distance in a direct line is hardly more than 

 half that. The ernptive rocks extend uninterruptedly from the mouth of the Jamei 

 across the ridge to the Majoma, and crossing that stream at its mouth, continue across 

 the JSfizao for a short distance, when their margin suddenly bends northward, running 

 along the ridge which divides the tributaries of the Majt)ma from the JN^izao, and con- 

 tinues to Mt. Vauilejo previously described. Beyond this western margin as on the 

 eastern side of the mass, dykes run out into green and broAvn jaspery slates, making 

 a perfect repetition of the condition of aflairs on the Upper Isigua and Jaina. The 

 sj^enites have been so thoroughly described alread}^, that it is hardly necessary to say 

 more than that they show no new features. On the Arroyo Botiguela, a little branch 

 of the "Nizao, dykes exactly like those at Madrigal on the Jaina were encountered, 

 and specimens from the one place, showing the contact between syenite and slate, are 

 undistinguishable from those from the other. At this place there is a beautiful fall 

 over the green jasper, the water giving a clear leap of eighty feet. The country is 

 entirely uninhabited, and except on its margins is never penetrated even by the pig 

 hunters. It is entirely w^ithout trails, and we were obliged to chop our road through 

 the primeval forest, with its dense undergrowth all of the way. The settlements on 

 its western margin extend but a mile or two east of Maniel ; while the last houses on 

 the iNTigua are at Jamei. Rancho Arriba further north is the only spot in all the 

 tract where there is any kind of a house; and that is about one-half ruined, and used 

 only occasionally by hunters, or as a stopping place by the very few persons who 

 cross the mountains by the Vanilejo route. 



Maniel is a thriving little town on the west bank of the Ocoa, the centre of a good 

 sized settlement in a valley 1,55-1 feet above the sea, according to the measurements 

 of Mr. PennelL Around it there is an unusually great variety in the rocks. Ten 

 miles above on the river we found drab-colored argillaceous limestone, with other 

 beds of a darker color with seams of white calc-spar. There is also much clay slate 

 and coarse sandstone, and near the town w^e found the same rocks repeated and 

 associated with conglomerates. Some of this is barely more than a very coarse 

 sandstone, the grains being almost uniformly of from an eighth to a quartei' of an 

 inch in diameter. In other places it is similar to specimens found near la Yeja, a. 

 green highly metamorphosed rock with small pebbles ; while again to the east of the 

 town, towards the Loma de los Ranches, it is a coarse sandy limestone, very full of 

 pebbles and resembling some of tlie fossiliferous limestone of the ISTigua in this 



