30 



COMMERCIAL FISHERIES REVIEW 



Vol. 28, No. 11 



area 2 mile square. A sample of peat from 

 this locality was studied in collaboration with 

 Dr. K. O. Emery of the Woods Hole Oceanog- 

 raphic Institution and Dr. M. Rubin, U.S. Geo- 

 logical Survey. 



This peat is a brown-colored compacted 

 mass of plant fibers, predominantly salt- 

 marsh grass (Spartina), containing numerous 

 twigs of woody land plants. Twigs and pollen 

 were mainly spruce with some pine and fir; 

 spores were largely from peat moss ( Sphag - 

 num ). Freshwater diatoms and rootlets of 

 cedar were also present. Numerous borings 

 contain specimens of Zirfaea crispate, a bor- 

 ing clam sometimes referred to as the Rough 

 Piddock- -alive at the time of the collection. 



The presence of many rhizomes of salt- 

 marsh grass is of particular interest because 

 this grass inhabits a rather limited range be- 

 tween mid-tide and high-tide levels. It thus 

 marks a past sea level rather accurately. 



Radiocarbon dating showed that the peat was 

 formed 11,000 (t 350) years before the present, 

 or about 9,000 B. C. This deposit is believed 

 to be the oldest submerged salt-marsh peat in 

 the world. 



Evidence from numerous sources indicates 

 that the enormous glaciers which pushed south- 

 ward across New England during the Pleisto- 

 cene Epoch retreated from the Connecticut 

 coast more than 13,500 years ago, from Mar- 

 tha's Vineyard 12,700 years ago, and from Bos - 

 ton 12,300 years ago. The sample described 

 here indicates that 11,000 years ago sea water 

 stood at a level 32 fathoms below present-day 

 sea level. The area presently known as Geor- 

 ges Bank was then an ice-free island. It may 

 be called St. Georges Island in keeping with the 

 bank's earlier name --St. Georges Bank. The 

 peat offers the first solid evidence that Geor- 

 ges Bank was previously an island. Elevation 

 of the island above sea level after the glaciers 

 retreated and the peat was forming is estimated 

 to have been 100 feet or more. At about that 

 time the island was covered, at least in part, 

 by boreal forests and salt-marsh grass in- 

 habited the lowland areas bordering the es- 

 tuaries and lagoons. The continued rise in sea 

 level from the glacier's melt-water drowned 

 the marshes and lower elevations. The re- 

 maining island was subsequently eroded away 

 by winds and waves accompanied by strong tidal 

 currents which reduced the is land to its pres- 

 ent state as a shallow bank. (A technical ac- 

 count of this study was recently reported in an 

 article by Emery, Wigley, and Rubin 1966.) 



FOSSIL TREE 



A piece of silicified tree limb (fig. 4) was 

 also dredged by the scalloper Ruth Lea from 

 the same locality (w e s t e r n end of Georges 

 Bank) where the peat was found. This speci- 

 men was originally about 18 inches long and 3 

 to4 inches in cross section. The oxidized out- 

 er layer is white and has a somewhat flaky 

 structure. This layer, absent in some places, 

 has a maximum thickness of ^ inch. Contrast- 

 ing sharply with the outer layer is a very dense, 

 well-preserved inner portion that is gray with 

 numerous closely spaced black streaks. These 

 features are evident on the cross -section cut 

 shown in the photograph. The gray-black inner 

 portion is about as hard as marble. 



Fig, 4 - Oblique view of silicified portion of tjie tree Euptelea , an 

 extinct species. 



Dr. Richard A. Scott of the U. S. Geological 

 Survey identified this specimen as a portion of 

 a dicotyledonous t r e e, family Eupteleaceae, 

 genus Euptelea . The species is new to science, 

 and the Georges Bank specimen is the only rec - 

 ord so far known. It is currently being studied 

 by Dr. Scott. His research has revealed that 

 the occurrence of the genus Euptelea off Mas- 

 sachusetts is the first record for this region 

 of the United States and the second record of 

 its occurrence in the New World. Two living 

 relatives of this fossil species occur in Asia: 

 one species lives in Japan, the other in China 

 and India. 



This tree is believed to have lived during 

 the early part of the Tertiary Period, 40 to 75 

 million years ago, although an even older, late 



