778 ABSTRACTS OF PAPERS 



Three-fourths of the state is occupied by roclis of either Pennsylvanian or 

 Permian age, the former being approximately 15,000 feet thicli and' the latter 

 from 3,000 to 4,000 feet thick. Cretaceous rocks outcrop in southern and 

 western Oklahoma and Tertiary deposits occur on the high plains in the west- 

 ern part of the State. Among the important problems yet to be solved are 

 the following: 



Petrology of the igneous rocks. 



Paleontology of the Ordovieian formations. 



Age of the Woodford chert. 



Relations of the Standley and Jackfork formations. 



Cause of the thickening of the Pennsylvanian sediments southward. 



Source of the Pennsylvanian and Permian sediments. 



Origin of the iron in the Red beds. 



Origin of the gypsum. 



Age of Cretaceous outlayers in western Oklahoma. 



Origin of the sand hills. 



OBSERVATIONS ON RATE OP SEA-CLIFF EROSION 

 BY CHARLES P. BEEKEY 



iAI)stract) 



Certain cliffs of unconsolidated materials along the Atlantic coast bear evi- 

 dence of comparatively rapid erosion. Reliable measurements, however, are 

 rare. Nearly all available data are estimates or generalities, based on the 

 destructive effects of some exceptionally severe storm. For the past year a 

 locality where such erosion prevails has been kept under observation. Meas- 

 urements have been made as often as any pronounced effect was observed. 

 The accumulated data are summarized, and their bearing on the question of 

 rate of cliff retreat is indicated. 



CLIMATE AND PHYSICAL CONDITIONS OP THE KEEWATIN 

 BY A. P. COLEMAN 



(Ahstract) 



Glacial conditions prevailed at the beginning of the Huronian, but hitherto 

 less has been known of the climate of the Keewatin. It is often referred to aa 

 essentially eruptive and with very different conditions from the present — hot 

 seas, etcetera. In Ontario, where the Keewatin is best displayed, it often in- 

 cludes thousands of feet of ordinary sediments, not only the puzzling iron for- 

 mation, but carbonaceous slate, ordinary slate, arkose, sedimentary mica 

 schist and gneiss, and crystalline limestone. The extent and character of 

 these sediments are such as correspond to ordinary weathering on a land 

 surface. They have often the composition of a clayey sand, such as could not 

 be furnished by volcanic products, though there may have been submarine 

 eruptions then, as now. The eastern Grenville series, in part probably equiva- 

 lent to the Keewatin, includes similar rocks, but with far more limestone. It 

 is essentially a sedimentary series. Most of the eruptives of the Keewatin 

 are surface volcanics or ash rocks. The sedimentary rocks imply land and 



