162 SOUTH AMERICA— THE ANDES REGIONS. 



mean depth of from 8 to 10 feet. The only deep basins now remaining are those 

 of the upland valleys, of which the largest is the Cocha, or " Lake " in a pre- 

 eminent sense. It floods an elevated cirque of the Pasto plateau, source of the 

 Guamoes affluent of the Putumayo, and stands at a probable altitude of over 8,200 

 feet. The early writers gave the Mar Biilce, or Great Lake of the Mocoas Indians, 

 as it was called, a far greater area than its real size, some 12 miles long with a 

 mean breadth of less than 3 miles. Although everywhere navigable, with depths 

 of from 15 to 35 fathoms, the Cocha does not give access to the Putumayo, its 

 effluent being interrupted by cascades and in places choked by vegetable growths. 

 Like Cocha, the Lake of Tota lies on the eastern slope of the Colombian Andes, 

 but drains through the Upia and Meta to the Orinoco. It fills a cirque in the 

 Sogamoso Mountains 9,790 feet above sea-level, and has an area of 24 square 

 miles, with an extreme depth of 180 feet. 



Climate of Colombia. 



If it is difficult to speak of a Venezuelan climate, the expression, "Colombian 

 climate," can still less be employed except in quite a special sense. A region of 

 such diveisitied relief, offering in its mountain ranges, plateaux, and terraces such 

 marked contrasts of altitudes and aspects, naturally possesses the whole series of 

 climates alternating with the seasons, and even from day to night. Every valley, 

 every slope has its special meteorological conditions of heat, winds, rains, and 

 atmospheric moisture. Hence the main climatic features can be indicated only in 

 a general way, regardless of the thousand local variations. 



In theory the thermic equator coincides with the low-lying Atlantic coast- 

 lands ; but here the heats are tempered by the moderating action of the sea 

 breezes, so that the Colombian " hells " lie farther inland. On the seaboard the 

 mean temperature is about 81"^ Fahr,, but on the llanos traversed by the Meta, 

 the Casanare, and the Arauca it rises to 90° and even 91° ; on all the open 

 plains at the east foot of the Andes it exceeds 87°, except in the southern regions 

 where begin the great Amazonian woodlands. 



In Colombia proper, between the various oordilleras that ramify from the 

 Pasto group towards the Caribbean Sea, the heats are all the more intense that 

 the cool trade winds are intercepted by the mountain barriers. Thus the lower 

 part of the Upar valley, lying under the shelter of the Snowy Sierra, has been 

 transformed to a sandy and marshy desert, with a mean temperature of 88° 

 Fahr., or 6° or 8° more than on the neighbouring coastlands. At Puerto Nacional, 

 on the Magdalena, the glass has often registered 104° in the shade. 



As a rule, the heat is considerably greater on the Atlantic than on the Pacific 

 seaboard. Thus Tumaco, on the south-west coast, not far from the equator, lies 

 under the isothermal of 79°, whereas the Groajira peninsula, washed by the 

 Caribbean Sea, over 600 miles farther north, has a normal temperature of 

 84°. From this it appears that the influence of Humboldt's cold Pacific current 

 is still felt as far north as the west Colombian coastlands. 



Thus relief, aspect, direction of aerial and marine currents are more potent 



