1853.J 



DAWSON COAL-MEASTJRES, NOVA SCOTIA. 



23 



inundated mud and sand was quite natural to the trees with Stigmarian 

 roots, is shown not only by instances in this section, but by a very 

 remarkable bed at Port Hood, Cape Breton, which I may refer to 

 here as belonging to precisely the same class of facts with that now 

 under consideration. 



A bed of sandstone, in the coal formation at Port Hood, is filled 

 with the stumps of large erect ribbed trees, with very distinct Stig- 

 marian roots of two species ; and more than one generation of trees 

 must have grown on the spot, since one large stump was observed to 

 be penetrated by the root of another tree, which must have grown 

 through it after it became filled with sand, fig. 3. Yet several of 



Fig. 3. — Stump of a tree penetrated by Stigmaria ; from the coal- 

 measures at Port Hood, Cape Breton Island. 



the layers of this sandstone are ripple-marked ; and the sandstone 

 immediately underlying one of the large stumps, which had been 



removed, was found to be distinctly 



Fig. 4. — Impression of tree- 

 stump in sandstone, with rip- 

 ple-marks ; from Port Hood. 



rippled, fig. 4 . At Port Hood the 

 beds dip gently toward the sea, 

 and at low tide a large surface of 

 the rock is exposed, with stony 

 casts of stumps projecting from it, 

 and Stigmaria-roots spreading in 

 all directions. 



Group XVIII. is a series of 

 sandstones and shales less perfectly 

 exposed than most other parts of 

 the section. Chocolate colours 

 prevail among the shales, and on 

 the whole this group presents few 

 indications of terrestrial condi- 

 tions. One of the beds, however, 

 has a surface with shrinkage 

 cracks, and we observed a bed of 

 erect Calamites and a Stigmaria- 

 soil. 



Group XIX. — The next ^oup 

 is of greater interest, showing seven soil-surfaces, intermixed with 



a. Kipple-raarks. 



