INVESTIGATION AND CONSERVATION OF THE EOCENE PIEDRA CHAMANA PETRIFIED FOREST, PERU

The Piedra Chamana Petrified Forest is located within the Sexi volcanic center in the northern Peruvian Andes about 100 km east of Chiclayo. The fossil trees occur in a volcaniclastic tuff dated by 40Ar/39Ar as 39 Ma, or late Middle Eocene. The fossil assemblage thus predates the major period of Andean uplift (late Miocene to Pliocene), although it was certainly associated with volcanic processes during the early evolution of these mountains.

Preservation of the fossil woods is good to excellent. Examination of a small sample indicates at least 7 dicots and 2 monocots, although we expect that larger collections will considerably increase the taxonomic diversity. Preliminary analysis confirms the presence of the families Fabaceae, Lauraceae, and Palmae, and the possible presence of Lecythidaceae, Myrtaceae, Rubiaceae, and Rutaceae. The woods provide an important source of new information about the development of tropical low latitude forests during the Cenozoic. Characteristics of the fossil woods provide a useful proxy for paleoclimate reconstruction, including new information about the evolution of rainforest vegetation and Paleogene climates in South America. A notable characteristic of the fossil material is the presence of rings that are more pronounced and more prevalent than in the present-day tropics outside of certain limited areas experiencing strongly seasonal flooding. On the basis of preliminary assessment of the woods and the geologic setting, we hypothesize that the Eocene forest is a high-diversity assemblage representing lowland or low-montane forest from the early period of Andean uplift with some floristic affinities to modern-day forests of the region, but growing in a climatic regime that was more seasonal than is typical in the tropical lowlands today.

Another component of our project involves advising the Peruvian authorities on issues of conservation of the site. The site first came to scientific attention in the early 1990s, and in 1997 it was designated for formal protection by the Peruvian government under the Cultural Patrimony of the Nation. The site is threatened because of increasing publicity. A site inventory to document baseline conditions and to establish a routine monitoring protocol is underway. Education and conservation measures are being developed to compliment potential ecotourism.