exactly the curve of the mainland, and is continued into Panama, under
the name of the Cordillera de Chiriqui. Its chief summits are Chirripo
Grande (11,485), the loftiest in the whole country, Buena Vista
(10,820), Ujum (8695), Pico Blanco (9645) and Rovalo (7050), on the
borders of Panama. Throughout the volcanic area earthquakes and
landslides are of frequent occurrence.

The narrowness of the level ground between the mountains and the sea
renders almost impossible the formation of any navigable river. The most
important streams are those of the Atlantic seaboard, notably the San
Juan, which drains Lake Nicaragua. Issuing from the lake within
Nicaraguan territory, the San Juan has a course of 95 m., mostly along
the frontier, to the Colorado Mouth, which is its main outfall, and
belongs wholly to Costa Rica. Its chief right-hand tributaries are the
San Carlos and Sarapiqui. The Reventazon, or Parismina, flows from the
central plateau to the Caribbean Sea; despite the shortness of its
valley, its volume is considerable, owing to the prevalence of moist
trade-winds near its sources. Six small streams and one large river, the
Rio Frio, flow across the northern frontier into Lake Nicaragua. On the
Pacific coast all the rivers are rapid and liable to sudden floods. None
is large, although three bear the prefix _Rio Grande_, "great river."
The Tempisque enters the Pacific at the head of the Gulf of Nicoya, and
tends to silt up that already shallow inlet (5-10 fathoms) with its
alluvial deposits. The Rio Grande de Tarcoles also enters the gulf, and
the Rio Grande de Pirris and Rio Grande de Terrabis or Diquis flow into
Coronada Bay. The Rio Grande de Tarcoles rises close to the Ochomogo
Pass and the sources of the Reventazon, at the base of Irazu; and the
headwaters of these two streams indicate precisely the depression in the
central plateau which severs the northern from the southern mountains.

Costa Rica is not differentiated from the neighbouring lands by any very
marked peculiarities of geological formation, or of plant and animal
life. Its geology, flora and fauna are therefore described under Central
America (q.v.).

_Climate._--Owing to the proximity of two oceans, and the varied
configuration of the surface of Costa Rica, an area of a few square
miles may exhibit the most striking extremes of climate; but, over the
entire country, it is possible to distinguish three climatic
zones--tropical, temperate and cold