OF SANTO DOMINGO. 183 



scattered through a gray mass, while in others there is hardly enough quartz and 

 feldspar together mixed through the mass of black hornblende crystals to separate 

 them one from another. In some cases the crystals are over an inch long and a third 

 of an inch thick, while the white minerals are in grains hardly coarser than sand. 



In the savana of Arbol Gordo and among the ruins of the old town of Buenaven- 

 tura I found pieces of bog iron ore in the form of a granular limonite. At the 

 former place I found it as loose pieces in the soil, especially in a narrow strip of 

 woods on the northern edge of the savana. Among the ruins I encountered squared 

 blocks of a cubic foot and a-half, which had been used in building one of the princi- 

 pal walls. Although my party was camped in this vicinity for weeks, and all were 

 specially charged to search for the oi'iginal deposit, Ave failed to find it. It must be 

 of considerable extent to have yielded the above blocks, but it is probably hidden 

 by surface soil. The absence of limestone in this vicinity would act as a serious 

 drawback to its exploration, should it be discovered even were the inducements for 

 working it otherwise good. 



The Mano River, the largest branch of the Jaina, enters that stream from the 

 west a short distance above Madrigal. Except near its mouth its whole course is 

 through a solid mass of syenite, the pebbles from which form a broad shingly bed. 

 In tirne of unusually heavy freshets the water spreads over the whole width, but at 

 other seasons it is confined to a narrow crooked channel. It adds no new facts to 

 our knowledge of the region, except the one that the great intrusive belt which sends 

 so many dykes across the J aina at this part of its course and through which the 

 upper part of the main river runs approaches bodily very near it, although it does not 

 quite reach it. Below the mouth of the Mano the Jaina channel divides ; one por- 

 tion carries all the water of the river in ordinary seasons, while the other runs on the 

 west side of an island and is only filled in times of extraordinarily high water. On 

 excavating two or three feet deep into this bed, water is reached at all times percola- 

 ting through the gravel. Here there is a little piece of flat river bottom made up of 

 sand and pebbles, and in 1869, Mr. Ohle " prospected " it thoroughly with a view to 

 beginning mining operations. He found gold in almost all of his pits, but did not 

 seem to discover sufficient in any one place to warrant further proceedings. 



South of the Madrigal on the eastern side of the river, although the hills still re- 

 tain for some distance a height of two or three hundred feet above the river, the 

 grassy surface of the savanas begins to encroach on the forest. The slates continue 

 cropping out to the surface in a few places for four or five miles here with n recog- 

 nizable high southern dip. until in th® Porto Rico SaA'ana, they are finally hidden by 



