20 A. Smith Woodiiwd — Notes on Argentina. 



concerning the Pampean Formation and the characters of the faunas 

 and floras of the same period. 



I can summarize everything relating to this question in this 

 form : — Absolutely no trace of glacial action is met with either ia 

 the Pampean Formation or in the immediately pre-Pampean de- 

 posits ; and no plant-species, no mammal, nor any species of mollusc, 

 whether marine, terrestrial, or fresh-water, indicating a climate colder 

 than that of the present day, is known from the base of the Monte 

 Hermoso horizon to the most modern of the Pampean deposits. 



Traces of ice-action in the form of ancient moraines, striated and 

 polished rocks, erratic blocks, etc., are confined to the modern for- 

 mations, post-Pampean, and always in the neighbourhood of the 

 mountains, proving a greater development of the snow-regions owing 

 to local physico-geographical causes of a very recent geological date. 



HI. — Observations on Senor Ameghino's "Notes on the Geology 



AND Paleontology of Argentina." 



By Arthur Smith Woodward, F.L.S., F.G.S. ; 



Of the British Museum (Natural History). 



THE general conclusions of the brothers Ameghino in reference 

 to the geology of Patagonia, as detailed in the foregoing 

 valuable synopsis of results, may be still more briefly stated in 

 the following manner : — 



(1) The oldest sedimentary rocks in which fossils have been 

 found are red sandstones, containing mineralized wood, Dinosaurian 

 bones, and other smaller reptilian remains. " Upper Cretaceous." 



(2) The terrestrial or fresh-water Fyrotherium Beds succeed these 

 and may be partly intercalated with them. They contain a singular 

 mammalian fauna, notably primitive Ungulata. "Upper Cretaceous." 



(3) For some distance from the present coast, but not far in the 

 interior, the Fyrotherium Beds are covered by the marine Patagonian 

 formation. " Upper Cretaceons and Eocene." 



(4) The Santa Cruz Formation, marine at the base but terrestrial 

 and fresh-water above (major portion), rests on the Patagonian 

 Formation near the coast, on the older rocks in the interior, and 

 contains a lai'ge mammalian fauna. " Eocene." 



(5) Next are local sheets of basalt, and a great " Boulder 

 Formation " proved to be of marine origin by the occurrence of 

 shells. "Miocene." 



(6) Uppermost lies the Pampean Formation, chiefly of marine 

 origin, with six or seven successive mammalian faunas. 



For the substantiation of these results we must still await the 

 publication of the sections and the detailed field observations of 

 Seiior Carlos Ameghino, which are already promised. Assuming, 

 however, that the stratigraphical succession here tabulated is correct, 

 the problem of the geological age of the various strata still admits 

 of discussion. It is well known that most authors disagree with 

 Dr. Florentine Ameghino in assigning the two early mammalian 

 faunas he distinguishes to so remote an antiquity as that which he 

 claims for them. It is clear that, judged by the standards of the 



