1853.] DAWSON COAL-MEASURES, NOVA SCOTIA. 25 



present mined. It commences with a black bituminous underclay, 

 probably a soil of long continuance ; it is filled with Stigmaj-iae. 

 It supports a bed of coal on which grew a forest of large trees, of 

 which a few very imperfectly preserved stumps alone remain. 

 Above this we have a succession of shales and coals vdth underclays ; 

 the shales having at one level an erect tree, and in several places an 

 abundance of prostrate plants. The surface was then covered with 

 water, depositing mud and fragments of plants to which the Spirorbis 

 attached its shells. On these sandstones Stiffmarice again took root, 

 and two beds are filled with well-preserved stools of these singular 

 roots, each with four main divisions branching dichotomously and 

 with rootlets attached. They must have grown on beds of argillaceous 

 and somewhat calcareous sand. The only result of the growth of 

 these dense forests was an inch of impure coal, over the highest 

 Stigmaria-bed . A lower and less important one supports an erect 

 ribbed stump. Above the coal last mentioned is a muddy underclay 

 with much vegetable matter, on which a varied and beautiful vegeta- 

 tion has flourished, and now lies prostrate in a thin band of shale 

 and ironstone. In this instance we found three species of Sigillaria, 

 aFavularia, and multitudes of Poacites and other leaves, as well as 

 Carpolites. Many of these fossils have Spirorbis attached. They 

 no doubt mark the site of a submerged and fallen forest, which 

 instead of appearing, like so many others, as a thin layer of coal, has 

 first served as a habitation for Spirorbis, and then been buried in 

 abundant deposits of clay and carbonate of iron. A little higher in 

 this group we find a thin coaly band, almost wholly composed of 

 Poacites. No roots appeared in the underclay, and it is consequently 

 possible that these leaves may have been drifted by water. On this 

 coal is a thick bed of shale, supporting two interesting erect stumps, 

 represented in figs. 6 & 6 a, ms. From the clay in which they are 

 rooted they pass upward through a sandstone 2 feet in thickness 

 into a shale with ironstone bands above. The smaller of the two 

 is ribbed, but without leaf-scars — its roots are concealed under the 

 beach. Opposite the sandstone the cast of the hollow trunk is of the 

 same material, but the sandstone within the bark rises 7 inches above 

 the surface of that without, showing that the sand bed was once thicker 

 than at present, and that a part of it had been removed from around 

 the stump before the deposition of the next bed. It is probable that 

 the level of the sand within the trunk was originally lower than that 

 without, and, if so, this sandstone may have lost much more than 

 7 inches. The larger stump, though rooted at the same level as the 

 smaller tree, is brought by the rise of the beds to a sufficient height to 

 allow its roots to be seen. It shows that while the sandstone within 

 these stumps rises higher than that without, it also descends lower, 

 though not quite to the roots, which with the base of the stump are 

 filled with clay. We thus learn that after the trunk became hollow, 

 and while its top continued to stand at least 3 feet above the surface, 

 it was partly filled with a deposit from muddy water. The mud 

 within was, however, much lower than that without, when sand 

 began to be deposited and filled the greater part of the stump. The 



