GIG STEVENSON— FORMATION OF COAL BEDS. [November 3, 



as well as by the more energetic bore, so that it projects as a prom- 

 ontory. Strahan^^" measured the section exposed during excava- 

 tions for docks on Barry island. The succession is 



I. Blown sand, Scrobicularia clay, sand, shingle, with strong line of 

 erosion below. 2. Blue silt with many sedges. 3. Upper peat bed, i to 2 

 feet thick. 4. Blue silty clay with many sedges. 5. Second peat bed, thin. 

 6. Blue silty clay with sedges. 7. Third peat bed. with many logs and 

 stools, roots in place underneath. 8. Blue silty clays with reeds, willow 

 leaves and freshwater shells. 9. Fourth peat bed with large trees and roots 

 in place and numerous land shells. 10. An old soil with roots and land 

 shells. II. Rock in place, at 35 feet below the Ordnance datum. 



Here as in the Carse area of Scotland, the peat underlies a 

 deposit containing marine shells. 



Lesquereux^^^ cites a French author, who found at many places 

 in the Department of Xord alternations of peat and sand, the latter 

 containing marine shells. He notes that when the growth of peat 

 is checked by dryness, a crust forms, which is a parting between the 

 old and the new peat. In the valley of the Somme.he found, under- 

 lying 8 feet of clay and concretionary limestone, 23 feet, 4 inches of 

 peat in 15 layers, with the partings distinct and the layers differing 

 in character. Alternations of clay, peat and calcareous concretions 

 are not rare. 



Geinitz,^^- more than twenty-five years ago, studied the dune- 

 covered bogs near Rostock. At a later period he had opportunity 

 for more detailed examination and his observations are important 

 from several points of view. At the bathing station near Graal. the 

 section shows at the bottom, sand of the Rostock plain, on which 

 rests a one-foot layer of peat, containing stumps of trees which grew^ 

 on it. The dune formerly covering this deposit has been removed 

 for some distance, exposing the peat, but it still remains at a little 

 way landward. Beyond the dune, one finds a forest of great beeches 

 and oaks, with the peat bed covering the surface between them. 



""A. Strahan, Mem. Geol. Survey, " (jeology of the South Wales Coal 

 Field," Part III., 1902, pp. 87-93. 



"' L. Lesquereux, Ann. Rep. 2d Geol. Survey of Penn. for 1885, pp. 116- 

 118. 



'^- E. Geinitz, " Nach der Sturmflut," Aus der Natur, Vol. IX.. 1908, 

 pp. 76-83. 



214 



