191 1] STEVENSON— FORMATION OF COAL BEDS. 615 



In America, observations as recorded are very few and, for the 

 most part, they are merely incidental, as until very recently the geo- 

 logical importance of peat was not recognized ; but in Europe the 

 case is very different ; one finds there such a wealth of illustration 

 as to cause surprise that any student should entertain doubts respect- 

 ing preservation of peat deposits by burial under sediments. A few 

 citations must suffice. 



J. Geikie^-* says that peat bogs often pass below the sea. In the 

 harbor of Aberdeen, trunks of oak are brought up and at a little 

 distance away, peat was seen below the sea level covered with lo 

 to 12 feet of sand. This bed, enclosing trees, is known to extend 

 for some distance into the bay. In the Carse lands, the river Tay 

 has cut down to a peat bog, now forming the river bed and under- 

 lying about ly feet of alluvial material, which near the top contains 

 cockles, mussels and other marine forms. This extensive peat de- 

 posit of the wide Carse area rests in part on alluvial sands and in 

 part on marine clays. The peat is highly compressed and splits 

 readily into laminze, on whose surfaces are small seeds and wing 

 cases of insects. As a rule, but not always, it is marked oft' sharply 

 from the overlying clay and silt. That it represents an old land sur- 

 face is certain but it is equally clear that, in great part, the vegetable 

 debris on top was drifted in from localities higher up in the valley, 

 for the upper part of the peat contains, at times, layers of silt and 

 twigs, while branches as well as trunks are scattered through the 

 lower 3 or 4 feet of the overlying silt. The conditions are the same 

 in Carse lands on both sides of Scotland and they exist in the 

 Hebrides. 



Prevost and Reade'-" have described a peat bed covered by a thick 

 deposit of sediments. The exposed portion is a dark-brown peaty 

 mass, containing large and small branches, roots and rootlets, the 

 latter passing into the underclay. Some large boles and an occa- 

 sional stump were seen on the upper surface. The authors note as 

 a remarkable fact, that this bed resists erosive action by the river 



'■^ J. Geikie, " The Great Ice Age," 1895, pp. 290-293. 



'"^ E. W. Prevost and T. :M. Reade, " The Peat and Forest Bed at West- 

 bury-on-Severn," Proc. Cottcsicold Xaf. Club, Vol. NIV., 1901. 



PROC. AMER. PHIL. SOC, L. 202 OO, PRINTED NOV. IJ, I9II. 



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