1S96.] PRAKGER. — A Submerged Pme- Forest. 157 



Two facts in the above description deserve our special at- 

 tention. Firstly, the trees were rooted in the peat, showing 

 that they g7'ew there, and were not drifted by currents or 

 carried down by streams. Secondly, the marine shells in the 

 overlying clay lived where we now find them. And thus we 

 obtain the key to this little earth-story. Fir-trees do not grow 

 in the sea, nor do marine shells flourish on dry land. These 

 beds of peat and clay tell us clearly of changes in the relative 

 level of land and sea. To appreciate these changes, and to 

 confirm our interpretation of the phenomena before us, we 

 turn to a locality where beds of this kind attain a more ex- 

 tensive development, and can be better studied than on the 

 storm-swept shore at Bray. The greater part of the City of 

 Belfast is built on thick deposits of post-glacia lage, and the 

 deep and wide excavations made from time to time in the con- 

 struction of new docks, have afforded golden opportunities for 

 their investigation — opportunities which have not been al- 

 together neglected. We will take a typical section from the 

 Alexandra Dock Works^ (fig. 2). 



Fig. 2. 



Surface layers, 



L. W. L •■- . • ■•..',; •■.:•■.• • • Sand and Clay 



" 6-6." 





Yellow Sand 2—0." 



Upper Blue Clay 

 6-0." 



Lower Blue Clay 

 6'-0." 



Grey Sand 2'— 0." 

 Peat r— 6." 

 Grey Sand 2'— 0." 



Red Sand i'-O." 



r^ Boulder Clay. 



» See Praeger, *• The Estuarine Clays at the new Alexandra Dock, 

 Belfast." Proc. B.N.F.C. for 1886-87, Apfendix. 



