1849.] 



BROWN ON THE SYDNEY COAL-FIELD, 



129 



a. Starting from the base of the section, the first erect tree is met 

 with in the bed of argillaceous shale No. 51, 222 feet above the mill- 

 stone grit. It is a fluted Sigillaria, 15 inches in diameter and 3 feet 

 high ; the base spreads out over the two-inch coal No. 50, but no 

 roots are visible. The interior of the stem is filled with argillaceous 

 shale. See Fig. 5. 



h. In the next superior bed of argillaceous underclay, two upright 

 stems of Sigillariae occur only 4 feet apart; one is 18 inches and 

 the other 27 inches in diameter at the top, their height being 4 feet. 

 The stems are fluted and covered with a bark of coal three-fourths of 

 an inch thick. They enlarge considerably as they descend, but no 

 roots are visible. We have here conclusive evidence that a slow and 

 gentle subsidence of the coal-measures was in progress during their 



Fig. 5. 



accumulation ; the two-inch coal No. 50, at one period the surface on 

 which the first tree grew, having subsided a depth of eight feet, the 

 shallow water was filled up with mud until it reached the surface, on 

 which the two trees in the underclay No. 52 flourished. 



c. At the height of 147 feet above the last trees, and 21 above the 

 Indian Cove Seam, two large stems of fluted Sigillarise with a coaly 

 bark half an inch thick occur ; their length is 5 feet and their dia- 



Fig. 6. 



meter at the top 24 inches, which increases rapidly as they descend, 

 but no traces of roots can be seen, owing to the soft carbonaceous 

 shale which underlies them having fallen away from beneath. 



d. About eight feet higher in the section, several erect Calamites, 

 from 4 to 8 feet in length and 3 to 5 inches in diameter, occur in the 

 micaceous sandstone No. 88. They do not present any traces of 

 roots. 



e. Erect Calamites, varying from 3 to 8 feet in height, and about 

 5 inches in diameter, are also met with in the bed of arenaceous 

 shale No. 119, being 151 feet above the sandstone No. 88, last men- 

 tioned. No roots are observable. 



