348 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1951 



There are older dates for geologic material than those above. Wood 

 from a peat bed in the Dranse Valley, south of Lake Geneva in France, 

 is reported as at least 19,000 years old. Wood and peat samples col- 

 lected between Chambery and Grenoble in southeastern France are 

 considered at least 21,000. Wood samples from the Lake Kickapoo 

 deposits at Wedron, 111., from the Camden Moraine south of Dayton, 

 Ohio, from a bank of Skunk Creek in Polk County, Iowa, and from 

 Vermilion County, 111., have been reported as older than 17,000 years. 

 Coaly peat from an exposure along Eagle River north of Anchorage, 

 Alaska, ran 14,300 ±600. Partially lignitized wood from the shore of 

 Tustermana Lake, Kenai Peninsula, Alaska, gave the date 15,800 ±400. 

 Wood from a depth of 30 to 60 feet along Fairbanks Creek, Alaska, 

 and associated with extinct mammal bones, dated 12,622 ± 750. A fos- 

 sil cedar log dredged from St. Georges Harbor, Bermuda, and repre- 

 sentative of the extensive forest that once flourished there but has long 

 been extinct, tested 11,500 ±700. 



Dates derived from pollen analysis and the radiocarbon determina- 

 tions show a general consistency, but there are some disagreements 

 which suggest that the stratigraphic position of some of the samples 

 was not determined properly. Also it seems that there may be a 

 possible source of error in a postdepositional replacement of carbon 

 14 by carbon 12. Several dates from bogs were mentioned in a previ- 

 ous paragraph. The results from a series of samples reflecting tree 

 growth in the eastern United States are interesting in that they show 

 that the pine phase was reached in West Virginia 9,423 ±840 years 

 ago at a time when that region was definitely outside the glaciated area. 

 The same stage was reached at 8,323 ±400 in Connecticut, and 

 7,988 ±420 in Minnesota in the region south of the limits reached by 

 the ice sheet during the Mankato substage. In northern Minnesota the 

 phase dated 7,128 ±300. It was still later when similar conditions 

 prevailed in northern Maine, as the radiocarbon test on material from 

 Plissey Pond gave the result 5,962±320 (Deevey, 1951). On the 

 basis of these figures it is easy to visualize the slow spread of pine 

 growth from south to north during the relatively dry climatic con- 

 ditions following the retreating ice sheet. 



Work on ocean samples has not progressed as far as that in other 

 lines of research, but what has been done indicates that useful informa- 

 tion will be forthcoming not only with respect to deposits at the bottom 

 of the sea but also pertaining to the age and movements of subsurface 

 currents. Unquestionably as more laboratories are established and 

 the techniques are perfected other fields will be found where radio- 

 carbon age determinations will have a definite place. There are, of 

 course, various aspects of the problem that still need clarification. 

 P'or example, it is not known what effect different climatic conditions 

 may have on samples, whether the carbon- 14 content is consistent in 



