40 PROCEEDINGS OF THE CHICAGO MEETING 



land area west of the present coast is discussed. From a consideration of 

 several different Pliocene floras from Bolivia, an approximate estimate is 

 given of the amount of uplift that has taken place since the Pliocene. Pale- 

 ontologic and topographic evidence is presented show^ing that a moderate 

 Tertiary elevation was followed by rather mature erosion, and this in turn by 

 profound elevation, which was accompanied by great igneous and volcanic 

 activity, the latter almost entirely confined to the western ranges. The bulk 

 of the mineralization also dates from this time, especially in the eastern 

 ranges of Bolivia, in which region this conclusion has been demonstrated. 



Presented by title in the absence of the authors. 



PRE-CAMIBRIAN ROCKS OF MANITOBA 

 BY F. J. ALCOCK AND E. L. BRUCE 



Printed in full in this volume. 



OCCURRENCE OF BASAL CONGLOMERATES 

 BY W. H. TWENHOFEL AND E. C. EDWARDS 



(Abstract) 



In many textbooks of geology the initial deposits over an unconformity are 

 represented as conglomerates or coarse sandstones, and the impress^ion is left 

 that such are the general accompaniment of an unconformity. Observations 

 made on many geologic sections show that such is not always the case, and 

 that the initial deposits in many cases are fine elastics, while coarser elastics 

 are altogether wanting or occur some distance above the initial strata. It 

 appears to have been the custom to refer the occurrence, where no coarse 

 elastics are present, to the invasion of the sea over a peneplaned surface, or 

 that a coast had been eroded of which the materials could not produce coarse 

 elastics. 



Observations made on many parts of the coast about the Gulf of Saint Law- 

 rence have led to the conclusion that gravels and coarse sands are not neces- 

 sarily the initial deposits of an invading sea, even under conditions of consid- 

 erable relief, and that it is equally as probable that the initial deposits above 

 an unconformity should be fine elastics. 



Presented in abstract by the senior author from notes. 

 Discussed by M. Y. Williams, with reply by W. H. Twenhofel. 



LLANORIA—THE PALEOZOIC LAND AREA IN LOUISIANA AND EASTERN TEXAS 



BY HUGH D. MISER 



{Abstract) 



Evidence for a Paleozoic land area that occupied at least a part of Lou- 

 isiana and eastern Texas has been published from time to time by different 

 geologists. The most important paper on the subject is one by J. C. Branner, 

 published in the American Journal of Science in 1897. Considerable informa- 



