Large Current-Ripples as Indicators of Paleogeography

The flora from Ptosi is extensive and not yet fully elaborated. It includes aboutsixty species and the following genera are represented: Acacia, Acrostichum, Amicia, Caesalpinia, Calliandra, Capparis, Cassia, Copaifera, Cuphea, Dalbergia, Desmodium, Drepanocarpus, Enterolobium, Escallonia, Euphorbia (?), Festuca, Gaylussacia, Gymnogramme, (?), Hedysarum, Inga, Lomariopsis, Lonchocarpus, Machaerium, Mimosa, Mimosites, Myrica, Myrteola, Passiflora (?), Peltophorum, Pithecolobium, Platipodium, Poacites, Podocarpus, Polystichum, Porliera, Ruprechtia, Sweetia, Terminalia, and Weinmannia. A perusal of these genera, already recognized, is sufficient to convince any botanist or indeed any visitor to the region, that this flora is very different from that now found in the Potosi region. While the botanical exploration of the present Bolivian flora leaves much to the future it is obvious that if we seek for representatives of this fossil flora in the recent flora of Bolivia, nearly all the genera are to be found represented in the more or less well watered country east of the present eastern range, and particularly on the lower eastern slopes. Moreover most of the fossil species are very close to still existing species of the latter region and this resemblance is so close that I cannot conceive of this flora being older than Pliocene. There is then definite evidence that parts of the high plateau and of the eastern Cordillera stood at sea level in the late Tertiary.