oi 10 



FERGUSON. 



The cliffs of the Piedmont region are composed of stratiiied sandstone 

 and conglomerate, poorly consolidated, and it is only the constant action 

 of the surf that permits such loose material to form cliffs. The pebbles 

 in the conglomerate beds are all of volcanic origin, and cross-bedding is 

 common in the sand and gravel layers, but no distinct ripple markings 

 appear. I found several pieces of wood embedded in various parts of 

 the cliffs, but never any marine shells. All these facts go to show that 

 the conglomerate is distinctly of terrestrial origin. However, northward 

 from Santo Domingo to Diojo Point there is a series of cliffs of coral 

 limestone interbedded with a distinctly marine conglomerate, the latter 

 containing a large proportion of limestone pebbles. The relations be- 

 tween this limestone and the conglomerate just described, which forms 

 the cliffs bounding the Piedmont area, is not entirely clear, but if the 

 coral has grown iipon the conglomerate, there maj' have been some slight 

 reworking of the material by the waves. The extremely flat plain of 

 Vergnung on the east coast opposite Santo Domingo seems to have been 

 planed off by marine action, as rounded pebbles and shells are found on 

 its surface. (See PI. VI.) It is of course possible that the lunestone 

 area north of Santo Domingo nray have been an earlier uplift against 

 which the wash deposits from the mountains have been built up. 



Santo Domingo de Basco, the capital of the subprovince and the 

 largest town in the islands, owes its prominence entirely to its situation. 

 It possesses the only harbor in the islands with a stretch of beach un- 

 obstructed by coral, where boats can be hauled up. It is surrounded Ijy 

 the best farming land and in addition it is the central point for the 

 fertile region around Moimt Iraya. 



Ibuj^ 



B&tST\ 



Cross Section alonj line A d CD (PI ate II) 



Scale /oo. ooo 



Fig. i. 



Pio-. i is a cross section through the islands of Ibujos, Sabtan and 

 Batan along the line ABCD of map 2, showing the principal features of 

 the topograjihy. 



