114 OlSr THE TOP()(iRAriIY AND GEOLOGY 



River. These streams, mountain torrents, roll and tumble over boulders, some ot 

 immense size and continue their course receivino- numerous tributaries until, half a 

 dozen miles below Jarabacoa, after receiving the Jimenoa, the Yaqui seems fully as 

 large as it is at Santiago. The trip from the valley to the mountain is one well worth 

 taking, giving one a new set of experiences, hardly to be obtained in any other part 

 of the Island so easily, if at all. I started in June, 1870, accompanied by several 

 persons, and eventually added guides and porters until we numbered, myself and 

 eight others — servants and employees. We started from the house of Col. Jose 

 Antonio Placencio, at Tabera on the Yaqui, a pretty spot, shut in among the hills, at 

 the foot of a high ridge ; almost at the southern border of the Miocene rocks. The 

 road commences to ascend the ridge within a few hundred yards of the house and 

 almost immediately entered into a region of metamorphosed Cretaceous slate standing 

 almost vertically. A climb of a mile, varied with an occasional descent, took us to 

 the summit of the ridge, along which we rode, through an almost unbroken forest of 

 large trees, past a settlement consisting of two or three houses in an opening, called 

 Aguacate, thence we descended to a pretty little mountain valley in a bend of the 

 Yaqui, called Humunucu, where a half dozen families live comfortably raising a few 

 pigs and cows and cultivating a little tobacco. Up to this point the slates had con- 

 tinued, sometimes magnesian, a little micaceous, but more usually jaspery; but they 

 now gave place to syenite, and in the crossing of a rivulet in the valley, I detected 

 the tirst crystallic rock, veiy much decomposed by exposure, but unmistakeable. As 

 is everyAvhere else the case, the slates, near the crystalline l ocks were rich in quartz 

 veins, and Placencio informed me that Avomen collect a little gold occasionally in the 

 streams. From Humunucu, we climbed another high ridge called the Loma de los 

 Caracoles, or Snail Hill, and descended a very steep trail again to the canon of the 

 river. On the south face of the hill, I foimd outside of the trail a mineral of rare 

 occurrence in Santo Domingo — a little concretionary mass, the size of a double fist, 

 of iron pyi-ites, bright and crystalline on fresh fracture, but so oxydized on the sur- 

 face as to have lost all structure and to appear a mere lump of ii'on rust. From 

 Humunucu, the entire region is a mass of syenite, all stratified rocks being left 

 behind. On reaching the canon we found a little flat of less than a hundred acres 

 through which the river runs, here a brawling stream, a dozen yards wide, tearing its 

 way over and among gray boulders or spreading out in sandy pools, but always in a 

 hurry, always running with a rapid current. 



This little ^ alle}^ retains the Indian name of Mana-bao* and is inhabited by two 



* These two syllables are frequently repeated in Santo Domingo, and as well as I can recall, always in connection 

 with streams — thus, Mana-guallata and Mana-Matuey, near Santo Domingo, and Bao or Ci-bao, the river from 

 which the valley and i-ange seem to have taken their name. 



