392 AMAZONIA AND LA PLATA. 



dangerous whirlpools. Such is the force of the currents and eddies that they 

 cause the plumb lines to drift, thus preventing accurate soundings from being 

 taken in these troubled waters. 



Climate of Argentina. 



With the exception of a small strip of territory in the extreme north, Argen- 

 tina lies entirely within the south temperate zone, with a climate corresponding 

 in some respects to that of west Europe, between the latitudes of Spain and the 

 Feroer Islands. But between 22^ and 25° south latitude there are naturally 

 many transitions from north to south, and to these must be added the changes that 

 take place from east to west between the Atlantic seaboard and the slopes of the 

 Cordilleras. Hence arises an endless diversity of local climates, all however 

 characterised both by a considerable range, and by sudden changes, of temperature. 

 The general relief of the land, from the plains of Chaco to the rugged Fuegian 

 Archipelago, leaves ample space for the play of the hot equatorial and cold antarctic 

 winds, which are nowhere intercepted by any mountain barriers. 



In the " Mesopotamian " region, and generally throughout North Argentina, 

 the normal currents set in the same direction as the mountain ranges and 

 watercourses, that is, from north to south, or from south to north, parallel with 

 the Andes and with the Famaiina and Aconquija foothills, parallel also with the 

 Parana and Uruguay valleys. But a certain see- saw movement is observed 

 between the eastern fluvial and the western highland regions. In the former the 

 northern, in the latter the southern currents predominate. 



Another contrast consists in the deflection of the north wind, which frequently 

 sweeps from the uplands down to the plains. This is the much-dreaded zonda, 

 which assumes the character of a gale, especially during the winter months from 

 July to September. Both the true north wind and the zonda are accompanied by 

 a considerable rise in the temperature, which has occasionally exceeded 104^ Fah. 

 Then any sudden shifting of the currents may be attended by a fall of 50° or 

 even 54^ Fah. within the twenty-four hours. 



In winter, and under the prolonged action of the south wind, which clears the 

 sky and promotes radiation, the glass may fall below freezing-point, and the Pata- 

 gonian rivers, as far north as the Chubut, rapidly freeze. Such is the purity of 

 the atmosphere, that at San Juan, near the foot of the Andes, the stars are said 

 to be visible by day, even in the vicinity of the sun. 



The coastlands about the Plate estuary and along the Atlantic seaboard enjoy 

 the alternating rirazones, land breezes prevailing during the day followed by sea 

 breezes at night. This region is also exposed to the south-east trades, not only 

 in summer, but also during a great part of the winter season. They sometimes 

 blow with fury, and under the name of sii-cstada they churn up the estuary waters 

 and stem the current of the Parana and Uruguay, causing these rivers to over- 

 flow their banks. Most of the shipwrecks in the Buenos Ayres roadstead are due 



