APPENDIX B
Fossil Determinations
A few fossil collections were gathered in order that age determinations might be made. With the following identifications I have included a few fossils (I and II) collected by W. R. Rumbold and put into my hands in 1907. The Silurian is from a Bolivian locality south of La Paz but in the great belt of shales, slates, and schists which forms one of the oldest sedimentary series in the Eastern Andes of Peru as well as Bolivia. While no fossils were found in this series in Peru the rocks are provisionally referred to the Silurian. Fossil-bearing Carboniferous overlies them but no other indication of their age was obtained save their general position in the belt of schists already mentioned. I am indebted to Professor Charles Schuchert of Yale University for the following determinations.
I. Silurian
San Roque Mine, southwest slope of Santa Vela Cruz, Canton Ichocu, Province Inquisivi, Bolivia.
Sent by William R. Rumbold in 1907.
- Climacograptus?
- Pholidops trombetana Clarke?
- Chonetes striatellus (Dalman).
- Atrypa marginalis (Dalman)?
- Cœlospira n. sp.
- Ctenodonta, 2 or more species.
- Hyolithes.
- Klœdenia.
- Calymene?
- Dalmanites, a large species with a terminal tail spine.
- Acidaspis.
These fossils indicate unmistakably Silurian and probably Middle Silurian. As all are from blue-black shales, brachiopods are the rarer fossils, while bivalves and trilobites are the common forms. The faunal aspect does not suggest relationship with that of Brazil as described by J. M. Clarke and not at all with that of North America. I believe this is the first time that Silurian fossils have been discovered in the high Andes.
II. Lower Devonian
Near north end of Lake Titicaca.