250 PATAGONIAN EXPEDITIONS! GEOGRAPHY. 



of the waters for a distance of some three hundred miles to the eastward 

 of these ports. Both these conditions conspire to produce a piling up of 

 the waters along this coast, which is most noticeable at Gallegos, since it 

 is situated nearest the apex of the bight. 



CLIMATE. 



As in all other parts of the earth's surface which fall within the limits 

 of the temperate zone, and where there are diversified physical features, 

 more especially high mountains and low and level plains, Patagonia 

 exhibits a considerable diversity of climate. / That of the west coast is, as 

 we have already seen, characterized by an extremely abundant precipita- 

 tion. / Rain or snow falls so constantly throughout this region that storms 

 of either are not only of daily, but almost hourly occurrence.* It thus 

 happens that not only the herbage, but the surface covering of vegetable 

 mould, as well as the underlying soil, are kept constantly drenched with 

 moisture. These conditions give rise to a most prolific vegetation, which, 

 for abundance, is surpassed in but few other portions of the world. 

 / On the plains east of the Andes other and quite different climatic 

 conditions obtain. <,! have already stated that the prevailing winds of 

 this region come from the southwest, or are at least westerly. I have 

 also explained how these winds, during their passage over the Andes, 

 have been deprived of most of their moisture, and hence reach the plains 

 region in a comparatively desiccated condition, and unable to contribute 

 much to the annual rainfall of that district. Owing to the lower altitude 

 of the plains, the atmosphere tends to become warmer and consequently 

 less dense than that to the westward. This causes the colder air of the 

 more elevated mountainous district to sweep down the eastern slopes of 

 the Andes and across the plains to the Atlantic. As this colder stratum 

 of air approaches the Atlantic, it comes successively more and more in 

 contact with the warmer airs bordering on that ocean. These have 

 already derived a considerable amount of moisture from the Atlantic, and 

 through the reaction of the colder air from the west, by which they are 

 forced upward, and their temperature is still further reduced, this moisture 

 is condensed and appears as low-hanging clouds, or is sometimes precipi- 

 tated, usually in the form of fine rain or snow, which, driven by the 

 almost constant and, at times, furious winds, augments this already disa- 

 greeable feature of the climate. It thus happens that, while the climate 



