18 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 2, 



beds is a large erect stump, filled with laminated clay after the com- 

 plete decay of its wood. In the clay filling it were abundance of Fern- 

 leaves, Poacites, Lepidophylla, a few plants with attached Spirorbis, 

 and a shell of Modiola. This tree was rooted in a thick underclay 

 full of rootlets of Stigmaria. Higher up there are several thin coaly 

 bands, with underclays ; many of the shales abound in leaves of 

 Ferns and Poacites, probably drifted, and the highest sandstone 

 showed a large erect tree. 



Group XI. commences vdth a soil resting immediately on the 

 truncated top of the tree last mentioned. On this soil was formed a 

 deep swamp, now represented by 5 feet of coal and bituminous shale 

 in alternate bands. Large quantities of clay and sand buried this 

 swamp, but not in such a manner as to preclude the growth of trees, 

 many of which were entombed in the erect position. In these sand- 

 stones and shales, no less than six erect trees were observed at dif- 

 ferent levels, the lowest being rooted in the shale forming the coal- 

 roof : 1 5 feet of the trunk of one of these trees still remain ; two 

 others were respectively 5 and 6 feet high. Erect Catamites were 

 also observed. The soil which was formed on the surface of these 

 beds supports one of the thickest coal-beds in the section, mark- 

 ing a long and undisturbed accumulation of vegetable matter. It 

 was covered by clay, which became a Stigmaria-soil, and was then 

 submerged for a sufficient time to allow the formation of a small bed 

 containing Cypris and Spirorbis. Above this we find a series of 

 beds indicating swamp conditions, alternating with aqueous drift and 

 deposition, and finally again giving place, for a long period, to the 

 quiet estuary or lagoon, inhabited by Modiola and ganoid fish, and 

 receiving little mechanical sediment. We have here, as in some pre- 

 vious groups, three distinct conditions of the surface : — first, terres- 

 trial surfaces more or less permanent ; secondly, undisturbed marine 

 or brackish water conditions ; thirdly, intervening between these the 

 deposition, probably with considerable rapidity, of sandy and muddy 

 sediment. We may also observe that, admitting the Stigmarice to be 

 roots of trees, there are five distinct forest-soils vrithout any remains 

 of the trees except their roots ; and we shall find throughout the sec- 

 tion that the forest-soils are much more frequently preserved than 

 the forests themselves. 



The Xllth Group, 80 feet in thickness, consists of sandstones and 

 shales, with few vegetable remains. There are, however, several 

 underclays, and one thin coal, and erect stumps appear at five 

 distinct levels. One of them is the largest tree observed in the sec- 

 tion : it measured 4 feet in diameter, and was 5 feet in height. Its 

 surface was irregularly ribbed, and it was rooted in clay containing Stig- 

 maria-rootlets. Its roots, however, were too imperfectly preserved to 

 show the markings, of Stigmaria. In this group we have probably 

 the margin of alluvial deposits, gradually spreading over the Modiola- 

 inhabited waters of the last group, and occasionally presenting dry 

 surfaces for a time sufficiently long to admit of the growth of trees of 

 great size. 



In the large series of beds included in Group XIII., there are no 



