Manual de Plantas de Costa Rica | The physical environment| TB 
Vieja (Cerros Atravesado, Cafias Dulces, Fortuna, Gongora, San Roque, etc.), near 
Miramar (Cerro San Miguel), and along the Rio Lori, on the Caribbean slope of the 
Cordillera de Talamanca. 
Neogene plutonic rocks in Costa Rica are mainly gabbros, granites, and granodi- 
orites, mostly acidic in composition. These occur along the Rio San Carlos, in the Cor- 
dillera de Tilaran (Guacimal formation), in the Cerros de Escazu, along the crest of the 
Cordillera de Talamanca (including Cerro Chirrip6, the highest peak), and in the Fila 
Costefia. See Weyl (1980), Castillo-Mufioz (1983), and Tournon & Alvarado (1997) for 
more information. 
Costa Rican sedimentary strata of Neogene origin include limestone, sandstone, 
conglomerate, siltstone, and shale, often intermixed in various combinations. Lime- 
stone is represented in ostensibly Neogene formations of scattered occurrence, most 
notably in hills at the head of the Gulf of Nicoya (Barra Honda formation), near Venado 
de San Carlos (Venado formation) and at Patarra and near Aserri (San Miguel lime- 
stone), along the south edge of the Central Valley. The exact age of the Barra Honda 
formation is unknown (it may well be Paleogene). Coral headlands, from exposed reefs 
extending into the Pleistocene or beyond (Limon formation), are a feature of the 
Caribbean coast south from the vicinity of Puerto Limon. Neogene sandstone is ex- 
posed in the Limén Basin, on the Nicoya Peninsula (west side and south tip), on Isla 
San Lucas, south of Puntarenas (Punta Carballo), near Tarcoles, in the Cerros de Es- 
cazu, on Alto Tablazo and Cerro Caraigres (north flank), on Punta Judas, in the Fila 
Costefia and Cordillera de Talamanca (including Cerro Chirrip6), and on the Osa 
Peninsula, among other places. See especially Castillo-Mufioz (1983) and Tournon & 
Alvarado (1997) for a much more exhaustive account of Neogene strata in Costa Rica. 
Quaternary rocks 
Virtually all volcanic cones and peaks in Costa Rica are of Quaternary age (except in 
the Montes del Aguacate; see above). Volcanic cones and hills on the northeastern Ca- 
ribbean coastal plain (Cerro Tortuguero, Lomas de Sierpe, Cerro Coronel) are also com- 
posed of Quaternary rock, as are some minor cones at the base of the Cordillera Cen- 
tral near Aguas Zarcas (Loma Juan Murillo, Loma Morera, etc.). 
Quaternary volcanic rock in Costa Rica may be andesitic, basaltic, dacitic, or rhyo- 
litic in composition. Rocks of this category not only compose the Costa Rican volca- 
noes and cones themselves, but also cover large adjacent areas of lower relief, mainly 
in the form of old lava flows, mudflows, and ash, sand, and gravel deposits from nearby 
volcanoes. Important Quaternary “volcanic fields” occur in the vicinity of Orotina and 
San Mateo (Tivives, Punta Loros, Pefi6n de Bajamar, Rio Surubres, Rio Jesus Maria, 
Rio Grande de Tarcoles, Hacienda Vieja, etc.), and at the base of the Cordillera Central 
on both versants of the Central Valley, downslope to near Hacienda Vieja on the Pacific 
side and to Turrialba on the Caribbean. 
