124 



ox TJIE TOlVXJliArilY Amj GEOLOGY 



the gj'assy slopes of the hills, nor in the " bottom," the position of the I'ocks over this 

 space is of course nncertain. • 



The belt of intrusive rocks (ISTo. 1) between Dajao and Guaraguano has little to 

 call our attention except some small patches where the syenite is of an unusually fine 

 texture. The quartz and feldspar in these specimens are unusually brilliant in lusti'e, 

 both being remarkably glassy, but the texture is so fine as to resemble in the mass a 

 fine black sandstone. I^orth of this, almost without the intervention of sandstone or 

 conglomerate, we have the same limestone repeated ; here the strike being continuous 

 and easily traceable to that near Las Matas. The dip also in this case is easily dis- 

 tinguished as a loAV one northward. Over the calcareous beds the shales dipping at 

 30° north extend northward and full of narrow seams of white quartz until they are 

 overlapped by the horizontal strata of a coarse sandstone, the latest Imown member 

 of the Tertiary of the valley, and which will be more full}^ described in connection 

 with the Mao gravels, of which it forms a part. 



The Mao Rivei' fui-nishes one of the best opportunities for a geological section of 

 any line running southward into the mountains in this vicinity. At'Latoma, o^^po- 

 site Dajao, on the west side of the river, the greenish talcosQ slates and clay stones 

 are remarkably full of quartz veins, and some stains of copper occur. A few years 

 ago, a Mr. Heneken (the same who published the i-emarkable description of the 

 geology of the Cibao), spent some time and considerable sums of money in searching 

 for copper here, with the success that is clearly predicted by the surface indications. 

 It is said also that he attempted to work some of the quartz ye'ms for gold ; but while 

 I encountered some of the " copper mines" I could find no traces of his gold mines. 



Quite close to the quartz-bearing shales, south of Latoma and almost opposite 

 Dajao, the syenite j-eappears, and resembles that north of Dajao in some respects. 

 The quartz and feldspar are both umisually glassy, and in this case the hornblende is 

 disproportionately abundant, reminding one somewhat of the rock on the J aina. Some 

 of the rock, on the other hand, is nearly pure quartz, and* veins of quartz are also 

 abundant here, as everywhere else. Other of it is dark gray, moderately coarse- 

 grained with the quartz, feldspar and hornblende in nearly equal proportions, and in 

 still other places, especially on the Cenoba River, it is gray with little or no horn- 

 blende, with peculiar small Avhite grains of feldspar, somewhat laminated, and contains 

 a little pyrites. " ■ : ■ 



From Dajao there is a trail, much used by the hunters of wild pigs and cattle, 

 which I'uns nearly south, following the summit of the ridges on the end which the 

 Dajao settlement is perched. About a mile back in the woods, and perhaps two from 



