Panama

PANAMA, a Latin American republic lying between Costa, Rica and Colombia, and occupying portions of the two geograph ical divisions, Central and South America; the Panama canal, crossing the narrowest and lowest point of land between the Atlantic and Pacific oceans, bisects the republic from sea to sea. The republic lies approximately between 7° 15' and 9° 39' N. lat. and between 77° 15' and 83° 30' W. longitude. It is bounded on the north by the Caribbean sea, east by Colombia, south by the Bay of Panama and the Pacific ocean, and west by Costa Rica. The area is about 32,800 sq.m. ; pop., exclusive of tl?e Canal Zone (1930), about 467,459, or about 12 to the square mile. The coast line on the Atlantic side is 477 m. and on the Pacific 767 miles. The greatest length of the country is 420 m. and the great est width 118 miles.

Physical Features.

The Isthmus of Panama, co-extensive with the republic, is the whole neck of land between the American continents ; in another use the term "Isthmus of Panama" is applied to the narrow crossing between the cities of Colon and Panama, the other narrow crossings, further east, being the Isth mus of San Blas (31 m.) and the Isthmus of Darien (46 m.). The use of the term "Isthmus of Panama" to include the whole country is becoming more common. The Caribbean coast-line is concave, the Pacific deeply convex. The Mosquito gulf is to the north west, the Gulf of Darien to the north-east, and on the north coast are several bays. Almirante bay, near the Costa Rican boundary, is 2 to 13 m. wide, with many islands and good anchorage, pro tected by Columbus island, about 8 m. long; immediately east of it, and connected with it, is Chiriqui lagoon (area about 320 sq.m.), 32 m. long, 12 m. wide at the widest point, with a maxi mum depth of 120 ft., protected on the sea side by Chiriqui archi pelago; immediately east of Colon, at the narrowest part of the isthmus, is the Gulf of San Blas, protected by a peninsula and by the Mulatas archipelago and having the excellent harbour of Man dinga in the south-west; still farther east is Caledonia bay with another good harbour. On the north coast there are about 63o islands with a total area of about 15o square miles. The Pacific coast is deeply indented by the Gulf of Panama, which is ioo m.

wide between Cape Garachine and Cape Malo, and has the Bay of Parita on its west side, north of Cape Malo, and the Gulf of San Miguel on its east side, north of Cape Garachine. Darien har bour, formed by the Tuira and Savannah rivers, is a part of the Gulf of San Miguel and is II m. long, 2 to 4 m. wide and nearly land-locked. In the Gulf of Panama there are 16 large and about Ioo smaller islands (the Pearl islands), with a total area of 450 sq.m., the largest being Rey or San Miguel (15 m. long and 7 m. wide), and San Jose (25 sq.m.) ; both are well wooded. West of the Gulf of Panama and separated from it by Azuero peninsula is the Gulf of Montijo, 20 m. long and 14 m. wide at its mouth, across which stretches Cebaco island, 13-1 m. long and 3 m. wide; west of Cebaco is Coiba, the largest island of the republic, 21 m.

long and 4 to 12 m. wide. (W. THo.) Geology.—The surface everywhere shows great irregularity, produced by heavy rainfall, which has developed a mature drainage system, and by marine erosion, shown by bold, rugged islands, such as those in the Gulf of Panama. There have been no active volcanoes in Panama since Pliocene time. A record of the earthquakes that have occurred in Panama from the time of the Spanish conquest until 1886 shows only two severe shocks, one in 1621, the other in 1882. The line of volcanoes in Mexico and Central America probably dates from the end of Cretaceous time. Great volcanism, which was accompanied by orogenic changes, occurred in late Cretaceous and early Tertiary time.

Most of the mountains of Panama were formed not by folding due to lateral pressure, as nearly all the mountains of western America are, but by intrusions of volcanic rocks as irregular cores, sills and dikes. The intrusive rocks include basalt, diorite, andesite, granodiorite and rhyolite. They were injected in a molten condition through masses of volcanic agglomerate, breccia and tuff, and sedimentary beds of sandstone, argillite, limestone and shale, nearly all of Oligocene age. Most of the intrusions that formed basalt, andesite and rhyolite seem to have occurred in Miocene time. The diorite is at least in part probably Eocene.