THE PTERIDOPHYTA AND THE PALEOENVIRONMENT OF THE MIDDLE PART OF THE LA TERNERA FORMATION (UPPER TRIASSIC) AT QUEBRADA LA CACHIVARITA, ATACAMA REGION, CHILE

Ten species of Pteridophyta from the middle part of the La Ternera For mation (Upper Triassic), in quebrada La Cachivarita, Copiapo Province, northern Chile, are described and figured. They include Rienitsia chi lensis, Todites chilensis, Todites sp., Neocalamites carrerel, Asterot heca rigbyana, Asterotheca fuchsi, Cladophlebis mendozaensis, Cladophl ebis kurtzi, Gleichenites cachivaritensis and Dictyophyllum (D.) tenui folium, being the first two, new ones: This assemblage agrees with an Upper Triassic age for the La Ternera Formation as formerly proposed. A sedimentological analysis of the section which includes the fossilif erous strata, recognizes five different facies which are interpreted a s deposits in a lake becoming progressively shallower.