8 University of Michigan 



highlands and along the western sides of the islands, at least 

 during the dry months. On the other hand, along the exces- 

 sively arid eastern shores and northern and southern tips of 

 the islands, a rather heavy dew formation seems to be the 

 usual thing. 



Lakd Habitats 



Sometime after the Miocene,^ the Dutch Leeward Islands 

 must have been almost entirely submerged ; so that they were 

 largely covered with a thick coral formation. Three or four 

 prominent beach-lines, around the hills (fig. iii-5), were 

 formed at different stages of the emergence, and the limestone 

 was eroded away from the central portions, so that the older 

 rocks were extensively exposed. Recently, another period of 

 partial submergence must have taken place, as the peculiar 

 shape of such bays as the Schottegat (Plate I, 5-R) and 

 Spaansch Water (2-E) on Curasao, certainly indicate that 

 these are sunken valleys. As the central dome was eroded 

 away, the stream channels formed narrow outlets through the 

 tilted limestone at the edges, and most of the present valleys 

 have a similar shape to these submerged ones. 



Fundamentally, on the basis of their igneous intrusions, the 

 Dutch Leeward Islands have been considered a portion of a 

 complex which includes the Goajira Peninsula and the Sierra 

 Nevada de Santa Marta (perhaps also the Paraguana Penin- 

 sula) of the South American mainland.^ Superficially, each 

 island is a canoe-anticline, the long axis of which extends 

 approximately northwest southeast. The central portion of 

 each island is composed largely of highly metamorphosed and 

 crumpled, Cretaceous conglomerate-schists, and of igneous 



8 Compare J. Lorie; 1887-9; Samml. Geol. Beichsmus. Leiden, 2 ser., 

 Bd. I, pp. 111-149; and K. Martin; 1887, 1888; Bericht iiber eine Beise 

 nach Niederldndisch Wcst-Indien, I and II. The latter contains a de- 

 tailed discussion of the geology of the three main islands, with rather 

 inelaborate maps of the formations. 



9W. Sievers; 1896; Petermanns Mitteilungen, Vol. XLII, p. 129, and 

 pi. X. 



