A13STRACTS OF PAPERS 129 



the Upper Devonian, but there is a progressive and rapid increase in tliose 

 forms whicli may be regarded as distinctively Mississippian. In general, the 

 Kinderhook is not separated from the overlying Osage formations by an ero- 

 sion interval, but the inauguration of a new stratigraphic division is indicated 

 by a more or less marked change in lithology and, more importantly, by the 

 introduction of faunas which are widely distributed and which in their cosmo- 

 politan character contrast strongly with the very provincial Kinderhook faunal 

 units. 



Eesults of field-work in paleobotan}^ and stratigraphy carried on during 

 the summer of 1922 under the auspices of the Carnegie Institution were 

 outlined by the author of the following paper : 



PALEOBOTANICAL C0NTBIBUTI0N8 TO THE STRATIGRAPHY OF CENTRAL 



OREGON 



BY RALPH W. CHANEY 



{Ahstract) 



The Crooked River occupies an area 30 to 50 miles south of the John Day 

 Basin, in central Oregon. A comparison of the Crooked River section as ex- 

 posed between Prineville and Paulina with that of the John Day Basin indi- 

 cates that the sequence of the formations is practically identical. The Crooked 

 River section shows several hundred feet of the Clarno formation with a char- 

 acteristic Lower Clarno flora, and up to 4,000 feet of the John Day series, 

 which carries near its base a flora similar to that of the Bridge Creek locality 

 in the John Day Basin. The lavas overlying resemble the Columbia River 

 lavas. A notable feature is the presence of dikes, which extend for over 

 twenty miles and appear to connect with the lava flows. The formations over- 

 lying the basalt have yielded no fossils as yet, but they show a close lithologic 

 similarity to the Mascall and Rattlesnake formations, which are the topmost 

 members of the section in the John Day Basin to the north. 



The flora of the John Day series includes over 25 species, most of which are 

 present at the Bridge Creek locality of the John Day Basin. Live oaks, birch, 

 poplar, elm, maple, sycamore, ironwood. and sequoia are among the more com- 

 mon forms. In the main these comprise a typical floodplain assemblage; the 

 oaks and poplars suggest ridges on whose dry slopes such xerophytic types 

 now live. A relatively high relief is also indicated by the local abundance of 

 sequoia, suggesting that during the Oligocene, as today, this moisture-requiring 

 form was limited to protected areas on the leeward sides of elevations. The 

 temperature and rainfall, as indicated by the flora, suggest a climate like that 

 in the north central United States. The recurrence of an identical flora in 

 several horizons may indicate the destruction of the earlier forests during 

 epochs of volcanic activity and their gradual development during the favorable 

 conditions of intervolcanic epochs. 



At 12.30 p. m. the meeting adjourned to the Michigan Union^ where 

 a complimentary luncheon was served to the members of the various 

 scientific societies in attendance. 



IX — Bull. Geol. Soc. Am., Vol. 34, 1922 



