:»22 



The An 





to count as an early human foothold. 

 Caves of Yucatan. Lippincott, Phila., 1895, p. 21) referring to the 

 rocks of Yucatan as of Mesozic Age, is at variance with the recent 

 observations of geologists, while Professor Holmes says on the other 

 hand, (p. 18): " The massive beds of limestone of which the Pe n 1 

 is formed contain and are largely made up of the remains of the 

 marine forms of life now flourishing, along the shores. Fossil shells 

 obtained from the rocks in various parts of the country are all of living 

 species and represent late Pliocene or early Plistocene times, thus 

 possibly bringing the date of the elevation of Yucatan down somewhat 

 near that of the reputed sinking of Atlantis, some eleven or twelve 

 thousand years ago, or not far from the period that witnessed the oscilla- 

 tions attending the glacial period." Though true that the peninsular 

 limestone is largely composed of existing marine forms we learn on 



Fig. 2. Examples of Terraces and Pyramids, superstructures omitted, 

 closer examination that it is not entirely so, and that the shells are not 

 all modern. We find that the full list of age denoting fossil mollusca 

 collected from the rocks of Yucatan by the expedition in 1891 of the 

 Academy of Natural Sciences of Philadelphia (See Geol. Researches in 

 Yucatan, by Prof. Angelo Heilprin, Proc. Acad. Nat. Sci. 1891. p. 

 136) does not characterize the Yucatan rock as of Plistocene Age 

 while the recent researches of geologists (Prof. J. W. Spencer makes 

 the Niagara Gorge 32,000 years old) now tend to add to the antiquity 

 of the Glacial Epoch. Professor If. : the Yucatan 



