xxxii THE COAST OF ECUADOR 483 



The Mangrove Zone (The Coasts of Ecuador and 



Colombia) 



We come now to thfe mangrove zone which comprises, with the 

 remarkable exception of a long stretch of arid sea-border to the 

 north of the Gulf of Guayaquil, the whole remaining western 

 sea-border of South America, namely, the Ecuadorian and Colombian 

 coasts. My own acquaintance with this region is limited to the 

 estuary of the Guayas or the Guayaquil River and to the southern 

 shore of the Gulf of Guayaquil ; but I am able to avail myself of 

 the researches of Baron von Eggers, which cover the entire 

 Ecuadorian coast ; and with Ecuador, therefore, I will bring this 

 brief sketch of the littoral flora of one side of a large continent to 

 a conclusion. 



The Ecuadorian coast, lying, as Baron von Eggers observes, 

 between the rainless and desert coasts of Peru and the " ewig 

 griine " coasts of Colombia, may be regarded as a transition-area 

 presenting very varied and complicated conditions. With the 

 cause of the remarkable contrasts exhibited by the strand-flora, 

 not only on the coast of Ecuador, but along the whole west coast 

 of South America through some forty-five degrees of latitude from 

 Patagonia to Colombia, I will presently deal. Here it may be 

 remarked in passing that the Humboldt Current has played the 

 determining part in producing the abnormal climatic conditions to 

 which these remarkable contrasts in the strand-flora of this coast 

 of the continent are mainly due. 



The mangrove zone, marking a more or less abrupt transition 

 from a region of drought and semi-sterility to one of humidity and 

 rank tropical vegetation, begins about lat. 3° 30' S, that is, in the 

 vicinity of Tumbez, or perhaps nearer the boundary-line between 

 Ecuador and Peru in lat. 3° 20' (see Note 72). Occupying the 

 southern shore of the Gulf of Guayaquil it extends up the Guayas 

 estuary to Guayaquil and rather beyond. But when we follow the 

 coast of Ecuador northward from the island of Puna towards 

 Santa Elena Point, we come upon one of the most remarkable 

 phenomena presented on the west coast of South America. The 

 dry region begins again and the mangroves disappear ; and these 

 conditions continue through about 2^ degrees of latitude until we 

 reach the equator, when the mangrove zone soon recommences, 

 and, as I infer, continues northward without a break to the coast of 

 Central America. 



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