COLOMBIA 85 part of the isthmus are covered with luxuriant and almost impenetrable forests, and are little known. The whole Atrato valley was once a vast estuary of the sea, whose waves broke upon the very feet of the Cordilleras. The fossiliferous rocks near the head waters of the Tuira show that the country was at one time submerged by the Pacific ocean, shell fish of the same character as the fossils being found living both in the Pacific and the Atlantic at the present time. The swamps about the Atrato river rest on beds of gold-bearing clay, which the natives wash with considerable profit. Toward the close of the last century a channel was cut by a monk across the so- called isthmus of Raspadura, connecting the head waters of the Atrato and of the San Juan, passing near Quibdo, lat. 5 50' IT., by which communication by boats is still maintained be- tween the Atlantic and the Pacific. The val- ley of the Cauca, between the W. and central ranges of the Cordilleras, is one of the richest, most fertile, and most populous districts in South America. It consists of two plateaus of different elevation and temperature. The soil is deep, and tinged with a red or yellow color. The pastures are rich, and the lands are well cultivated. The valley of the Magda- lena comprises an area of about 75,000 sq. m. The soil is very fertile, but the climate is hot, and in portions insalubrious. Owing to the wide ramifications of the Andes, a large part of Colombia lies at an elevation of from 5,000 to 10,000 ft. above the sea ; but in consequence of the unhealthfulness of the coast and the in- accessibility of the mountain passes, the great resources of the country are comparatively undeveloped. On the east the river Orinoco forms a part of the boundary line between Colombia and Venezuela, and on the south the Putumayo separates it from Ecuador. Into the former flow the Guaviare, Vichada, Meta, and a number of smaller streams. The princi- pal affluents of the Marafion or Amazon in the republic, besides the Putumayo, are the Rio Caqueta, sometimes called the Japura or Hya- pura, and the Rio Negro. The Vaupes or Ucayari is a branch of the latter. Colombia has the right of navigating the Amazon and the Orinoco. But the most important of all its rivers is the Magdalena, with its tributary the Cauca. They traverse nearly the entire country from N. to S. They both rise in the Andes, about lat. 2 IS"., and pursue a nearly parallel course, the former on the east and the latter on the west of the central range, until they unite in lat. 9 20' K, again to divide in lat. 9 57', and fall into the Caribbean sea by two deltas, one in lat. 10 and the other in lat. 11 7', forming an island of 3,150 sq. m. The Magdalena, navigated by steam to Honda, is on an average 1,750 ft. lower than the Cauca, whose stream is therefore very impetuous. The Funza, which rises 100 m. 1ST. of Bogota, runs in a S. W. direction to Tequendama, where it plunges down a precipice over 600 ft. high, falling from the region of oaks, willows, and wheat, to that of the palm and sugar cane. The Atrato rises in lat. 5 20' N., flows N., and falls into the gulf of Darien. To the dis- tance of 180 m. from the sea it is deep enough for the largest ships ; and extensive traffic be- tween Quibdo and Cartagena is carried on by bongos, or large canoes. The navigation of this river and those of the isthmus was pro- hibited on pain of death by Philip II., lest for- eign powers should gain a knowledge of means of connecting the two oceans. The rivers draining the W. chain of the Cordilleras into the Pacific are small. The most important are the Patia and the San Juan, which communi- cate with the high, salubrious, and fertile dis- tricts of Popayan, Pasto, Tuquerres, and the famous valley of Cauca, which Bolivar called the "Italy of America." Small lakes are nu- merous in the mountains, but there are none of large extent. Paletara, Las Papas, Una, and Caucagua are the most noteworthy. Into Guatavita, a small lake near Bogota, the In- dians are said to have thrown their treasures when about to abandon the country to the Spaniards. Curious and valuable articles have been fished up from its depths, but at- tempts made to drain it have proved a failure. The geological conditions of Colombia are equally extraordinary and perplexing. Every- where are found traces of stupendous cata- clysms, and a disarrangement and intermixture of primitive and sedimentary rocks, which seem to set classification at defiance. In some places great rivers and even small streams have cut through mountains of the hardest rocks, leaving dizzy escarpments on each side; in others are enormous subsidences in the earth, as if the props of its surface had suddenly given way, or vast caverns glistening with stalactites ; while everywhere colossal masses, lifted high above the general level, attest the violence of volcanic agencies. These agencies are still active in places, as in Batan near So- gamoso, where the soil is so much heated that, although in the heart of the Andes, it pro- duces all the fruits of the tropics. The cele- brated Colombian geologist, Joaquin Acosta, describes great glaciers which he saw in the Paramo of Ruiz, a phenomenon which escaped the attention of both Humboldt and Boussin- gault. Col. Codazzi demonstrated that in the highlands of Bogota, Tunja, and Velez, where is now the densest population, there once existed a system of broad and deep lakes, which, breaking through their barriers, pre- cipitated themselves through what is now the river Suarez or Sogamoso into the ocean, leav- ing the traces of their irruption boldly marked on the face of the country. The same author- ity conceives that this great cataclysm may have occurred within the past four centuries. Some evidence in support of his theory is af- forded by two great stones which have been discovered on opposite sides of what must have been the borders of the principal lake ; both
