I'l') ox THE TOPOGKAPTTY AXD GEOLOCrY 



stone was found interstratilied with the talcose slate, and occasional quartz veins are 

 to be seen ; but nowhere does this quartz carry gold. A little north of San Jose, a 

 perceptible northern dip occurs, after which the rocks again become vertical ; but at 

 Bohio Viego, where I had a good opportunity for measurement, I found a due E. 

 and W. strike, with a dip to the S. of from 65° to 70°. xlt this point the margin of 

 the Miocene covers up the older formation, and it does not I'cappear. 



At the crossing of the Amina and again on the hill side, two miles west of San 

 Jose, there is an exposure of a dark bluish-gray limestone, so little altered that on 

 the hill I found a very faint trace of a coral on a weathered surface. This is the only 

 case where fossils of any kind have been found in the formation on the north side of 

 the island. The beds are not very thick, and dip into the hill in such a manner that 

 the angle could not be determined with any degree of accuracy, but so far as I could 

 determine, they have a strong northern dip. These limestones are intiuiately as- 

 sociated with and overlie the conglomerate beds found east of San Jose, and which 

 are again repeated on the next ridge west, there dipping at compai'atively low angles 

 northwards. 



The road from San Jose to Magna runs west until it crosses the Guanajuma, after 

 which it mounts a ridge, and follows its summit southwest to the arroyo Magna. 

 Here for the first time it enters the eruptive rocks. One dyke, or perhaps it should 

 I'ather be called a streak in the mass, which extends from this point west to beyond 

 the Jicome Creek, being encountered at several points along the line, is characterized 

 by rather large ci-ystals of feldspar, having a peculiar greenish tinge, and by the 

 presence of small quantities of mica. At the crossing of the Magna, there were also 

 found other syenites diftering from this, the most marked being a wdiite variety, with 

 slender crystals of hornblende sometimes two inches long. This intrusive mass, 

 which may be called the first or oiTter belt, is not wide on the Magna, but widens out 

 and extends as an irregular strip to beyond Savaneta, disappearing under the Tertiary 

 gravels. 



Southwest of the little settlement at the crossing of the Magna, there is a road 

 across the hills to Dajao, following which we find ourselves very soon on sedimentary 

 rocks again. Plere, at the " Loma de los Minas," is a well-marked synclinal axis. 

 The above-mentioned dyke has formed an anticlinal, and another belt, InTo. 2, crossing 

 south of Dajao, foi-ming another, the country between the two is bent into a basin. 

 The dip on this hill is at high angles to the south, and the most common rock is the 

 same limestone as that just described as being found on and west of the Amina. It 

 is all more or less gray ; some is identical with that from the Amina, some is earthy, 

 with white streaks of calc spai". Under the limestone is a peculiar-looking bi-own 



