GEOLOGY AND MINING INTERESTS. The Andean ranges of the southwest arc for the most port of plutonic formation in which granite and gneiss predominate, with lateral ridges of upper green sandstone and limestone. The valleys and plains on either side of these ranges are covered by detrital deposits. The northernmost range of the coast system is of crystalline forma tion, but the lower southern chain is largely composed of stratified Cretaceous rocks. The soil throughout this whole region is very deep and fer tile, making it one of the richest agricultural centres of the continent. The Banos and the low lands of Maracaibo are largely made up of Ter tiary and Quaternary deposits. composed chiefly of marl, sand, shingle, and conglomerate mixed with alluvial deposits. The foundation of the Guiana highland region is of granite with an outer layer of sandstone, and large barren stretches occur in this region. The mineral re sources are supposed to be of great value, but are at present little developed. The greatest yield of gold is found in the Territory of Vuruari, though the exports of that metal from this region have fallen off greatly since the early eighties, when the annual yield averaged nearly 200,000 ounces.
The copper mines of the Aroa district, 70 miles west of Puerto Cabello, produce superior ore, but their yield has also greatly lessened within the last few years. The salt mines of the Araya peninsula, worked since the sixteenth century, form an important Government monopoly, and with other salinas often produce 100,000 tons annually. Copper, silver, and iron are abundant in the other mountainous regions of the Republic.
An inferior quality of coal is found near Barce lona and at the head of the Gulf of Paria. Rich deposits of asphalt are known to exist in the Maracaibo region and in the State of Bermudez, and petroleum of fine quality in the State of Los Andes. Excellent granite is found near Cart-teas and marble is common.