462 j. b. woodavorth caney shales at talihina, oklahoma 



Remarks on Carboniferous Climate 



The occurrence of isolated boulders in the coal measures of Xorth 

 America has long been commented on and usually referred to the action 

 of trees entangling boulders in their roots.^ The abundant evidence of 

 glaciation in the Permian and more remote periods now make it quite 

 as reasonable to suppose that ice formed on the fresh waters of the Car- 

 boniferous, and the boulders of the Caney shale, regardless of their striae, 

 greatly strengthen this view. The Roxbury, Dighton, and other con- 

 glomerates of the Carbonic system in Massachusetts and Rhode Island, 

 for which Professor Shaler jDostulated a glacial origin, appear to be tor- 

 rential fan deposits laid down in a valley or valleys of aggradation at the 

 side of a now eroded mountain mass. It may well be admitted that local 

 valley glaciers- were best calculated to produce the erosion of so much 

 coarse granitic and quartzite material, the rolled state of boulders and 

 pebbles being due to the action of glacio-natant streams. This view be- 

 comes a strong probability in the light of the remarkable breccia described 

 by Messrs. Sayles and La Forge in the Boston area, where a bed at the 

 top of the Roxbury conglomerate has all the mass characters of tillite. 

 including a few discoveries of pebbles with markings which the authors 

 named have not without many considerations in favor of their claims held 

 to be of glacial origin. This presumable tillite bed is possibh'' of Permian 

 age, but its association with the underlying conglomerates and similar 

 thick water-worn conglomerates of known Carboniferous (Alleghany) age 

 in the Xarragansett area points to the correctness of Shaler's theory of 

 the glacial origin of the conglomerates as a Avhole. 



The modern amphibia, described as "cold-enduring/' ''patient of 

 cold'^ by zoologists, underwent their first great development in the Car- 

 l)oniferous coal measures, and, if organic structure at so remote an epocli 

 carries any signihcance as to climate, would lead us to expect that the 

 Carboniferous climates of middle latitudes in the northern hemisphere 

 were cool rather than warm. Ulrich^*^ infers cool waters for the formation 

 of marine black shales, but these are more in evidence in the Devonian. 



Similarly in Europe, Julien has advocated the glacial origin of the 

 coarse Carboniferous breccias of central France, and Kalkowsky has 

 argued for the glacial origin of a pebbly shale in the Carboniferous 

 rocks of the Frankenwald.'^ 



In conclusion, it would seem possible to state that there is evidence for 

 presuming that the Permian glacial period was preceded in the Car- 

 boniferous by a degree of cold permitting of floating ice in continental 

 bodies of water and also in the sea in middle latitudes. 



sj. D. Dana: Manual of Geology. 4th od.. lSOr>. p. 004. 



"See A. Geikie : Text-book of Geology. 4th ed.. iro.'). vol. ii. p. 1000. with references, 



"Revision of I'aleozoic Systems, pp. 352 to 361. 



