140 PROCEEDINGS OF THE AMHERST MEETING 



were a phase of the building of the Andes system and appear to have been 

 repeated at different intervals during the geologic history of the region. The 

 most important deformation occurred subsequent to the deposition of the 

 Tatarenda formation, but earlier movements took place between the deposition 

 of the Bermejo series and the Tacuru formation, as well as between the laying 

 down of the Tacuru and Tatarenda formations. 



Presented in full extemporaneously. 

 Discussed by Charles Schuchert. 



Discussion 



Professor Schuchert: Students of South American historical geology -will 

 be thankful to Professor Mather for his account of the geology of a formerly 

 unknown region. It appears that his reconnaissance is in an area to the east 

 of the Andean geosyncline where no marine deposits of Pennsylvanian age 

 occur, and this seemingly explains why he found the Lower Devonian overlain 

 directly by Permian continental deposits. The seas of Lower Devonian time 

 were far more widespread than those of the Pennsylvanian. 



SOME ASTRONOMICAL TESTS OF THE PLANETESIMAL HYPOTHESIS 



BY HARRY FIELDING REID 



{Abstract) 



There are some remarkable characteristics of the solar system : the forward 

 revolution of the planets and of the satellites, the forward rotation of the 

 planets, the small eccentricities of their orbits, and the nearness of the planes 

 of these orbits to the invariable plane. Some calculations have been made to 

 test the efficiency of the planetesimal hypothesis to explain these characteris- 

 tics. The hypothesis of the origin of the spiral nebula? and of the solar planets 

 by the approach of a star is briefly considered. 



Presented without notes. 



MARGINAL BELTS OF THE CORAL SEAS 

 BY WILLIAM MORRIS DAVIS 



Presented extemporaneously, with lantern-slide illustration. 



TRANSGRESSIONS, REGRESSIONS, AND SHORELINE DISPLACEMENTS DIRING 



THE PLEISTOCENE 



BY CHESTER A. REEDS 



Read from manuscript. 



OLD AND NEW STANDARDS OF PLEISTOCENE SUBDIVISION 

 BY HENRY FAIRFIELD OSBORX AND CHESTER A. REEDS 



Read in abstract from manuscript by the junior author. 



