88 PROCEEDINGS OF THE SAINT LOUIS MEETING 



character of the hydrocarbons and general structural features, attention should 

 be given to the following considerations, in addition to the geographic arrange- 

 ment: (1) The fact that the strata are higher and the rocks more fractured 

 in the regions of uplift; (2) the possibility that the present areas of geanti- 

 clines were areas of uplift and the geosynclines areas of depression at the 

 time the strata were laid down, and that for this, and perhaps other reasons, 

 conditions and original deposits were different ; ( 3 ) other respects in which 

 the history and conditions likely to have affected the formation, retention, and 

 character of oil have been different; (4) the question of whether or not oil 

 and gas pools were formed in the geanticlines, and if they were, what was 

 their history and why are few, if any, traces left; (5) the extreme improba- 

 bility of thrust pressures affecting the fluids in rock pores to an extent greater 

 than 50 or 100 per cent above the hydrostatic head, for higher pressures would 

 presumably squeeze out the fluids, and differences in superincumbent load 

 seems to have little effect on the quality of petroleum; (6) the great and ap- 

 parently irregular quality variations of the hydrocarbons in short distances — 

 the innumerable and extensive departures from harmony among the data; (7) 

 the greater abundance of salt water in the geosynclines, indicating poorer 

 circulation; (8) the effects of filtration during migration of the oil; (9) the 

 quality of the relict portion of the parent material, particularly in any central 

 portions of the compressed areas where the pressure may have been locally 

 relieved; (10) the principles of physical chemistry that are concerned, par- 

 ticularly the possibility of pressure affecting the chemical transformations; 

 (11) the chemical reactions that may have been induced by substances other 

 than carbon and hydrogen and their compounds, such as sulphur, chlorine, and 

 clay. 



It seems to the writer (1) that more than one hypothesis is in accord with 

 most of the available facts and established principles; (2) that, contrary to 

 certain statements, no hypothesis thus far offered fits all the evidence; (3) 

 that probably there are several reasons why oil and gas occur mainly in geo- 

 synclines and more than one reason for the apparent relation between quality 

 and distance from centers of uplift; (4) that a basinward or down-dip migra- 

 tion has been general and has been at least a partial cause of quality relation- 

 ships, the gas perhaps tending to lag behind in the downward movement be- 

 cause of its extreme lightness, and possibly certain oils because of their great 

 viscosity. 



Eead by title in the absence of the author. 



NEW POINTS IN ORDOVIGIAN AND SILURIAN PALEOGEOQRAPHY 

 BY T. E. SAVAGE AND FRANCIS M. VAN TUYL 



{Abstract) 



As a result of a study of the early Paleozoic formations of the Hudson Bay 

 region and of Wyoming, new data bearing on the paleogeography of Ordovician 

 and Silurian time have been obtained. 



Presented by the senior author in abstract from notes. 



