380 COAL — FOSSIL FOEESTS OF NOVA SCOTIA. [Cn. XXIV. 



but supported by strong roots, may have resisted an incursion of 

 the sea. 



The high tides of the Bay of Fundy, rising more than 60 feet, are so 

 destructive as to undermine and sweep away continually the whole face 

 of the cliffs, and thus a new crop of erect fossil trees is brought into 

 view eveiy three or four years. They are known to extend over a space 

 between two or three miles from north to south, and more than twice 

 that distance from east to west, being seen in the banks of streams inter- 

 secting the coal-field. 



In Cape Breton, Mr. Richard Brown has observed in the Sydney 

 coal-field a total thickness of coal-measures, without including the 

 underlying millstone-grit, of 1843 feet, dipping at an angle of 8°. 

 He has published minute details of the whole series, showing at how 

 many different levels erect trees occur, consisting of Sigillaria, Le- 

 pidodendron, Calamites, and other genera. In one place eight erect 

 trunks, with roots and rootlets attached to them, were seen at the 

 same level, within a horizontal space 80 feet in length. Beds of coal 

 of various thickness are interstratified. Taking into account forty- 

 one clays filled with roots of Stigmaria in their natural position, 

 and eighteen layers of upright trees at other levels, there is, on the 

 whole, clear evidence of at least fifty-nine fossil forests, ranged one 

 above the other, in this coal-field, in the above-mentioned thickness 

 of strata* 



The fossil shells of Cape Breton and those of the Nova Scotia section 

 (p. 378) consisting of Cypris, TJnio (?), Afodiola, and an annelid proba- 

 bly of the genus Spirorbis (see fig. 498), seem to indicate brackish water; 

 but we ought never to be surprised if, in pursuing the same stratum, we 

 should come either to a freshwater or a purely marine deposit ; for this 

 will depend upon our taking a direction higher up or lower down the 

 ancient river or delta deposit. 



In the strata above described, the association of clays supporting up- 

 right trees, with other beds containing marine and brackish-water shells, 

 implies such a repeated change in the same area, from land to sea and 

 from sea to land, that here, if anywhere, we should expect to meet with 

 evidence of the fall of rain on ancient sea-beaches. Accordingly rain-prints 

 were seen by me and Mr. Dawson a!.; various levels, but the most perfect 

 hitherto observed were discovered by Mr. Brown near Sydney in Cape 

 Breton. They consist of very delicate impressions of rain-drops on green- 

 ish slates, with several worm-tracks (a, b, fig. 495), such as usually accom- 

 pany rain-marks on the recent mud of the Bay of Fundy, and other 

 modern beaches. 



The casts of rain-prints, in figs. 496 and 497, project from the under 

 side of two layers, occurring at different levels, the one a sandy 

 shale, resting on the green shale (fig. 495), the other a sandstone 

 presenting a similar warty or blistered surface, on which are also 



* Geol. Quart. Journ. voL ii. p. 393; and voL vi. p. 115. 



