216 Geological Society. 



on the spots where they are now found, and that they were not drifted 

 from distant lands, ]\Ir. Bowman says, the arguments in favour of 

 the formation of beds of coal by a series of subsidences of the sur- 

 face on which the vegetables that produced the coal grew, naturally 

 lead to the inference that the trees associated with the coal also 

 flourished on the same spots. In opposition to the opinion that trees 

 would naturally float in an upright position in consequence of the 

 greater specific gravity of the base and roots, he asserts, that the 

 trees would maintain that position only as long as they floated, and 

 that they would fall and lie prostrate when grounded on shoals or 

 cast ashore. He agrees w-ith Mr. Hawkshaw in the opinion, that 

 it is more difiicult to account for a number of great trunks being de- 

 posited in the position of the fossils in the Manchester railway, than 

 to imagine that they grew on the surface of the bed on which they 

 now stand. Their position on a bed of coal is another proof, Mr. 

 Bowman conceives, that the trees were not drifted, for if they had 

 been transported by currents of water they might equally have been 

 imbedded in the alternating shales or sandstones. If beds of coal 

 are the accumulated remains of many generations of a luxuriant ve- 

 getation, the rich compost thus formed, Mr. Bowman argues, would 

 be well suited for the growth of trees. Again, the angle at which 

 the roots of the fossil trees, particularly of that distinguished by him 

 as No. 2, dip towards the bed of coal, is considered by the author 

 evidence of the trees being in their original position, because, had 

 they been drifted, the roots would have been bent upwards, by the 

 downward pressure of the trunk, when the water had left them. 

 The appearance of the roots being cut ofi^, where in contact with 

 the coal, he is of opinion, may be explained by the fermentative 

 process having dissolved the vegetable texture below the surface. 

 The stems and upper portions of the roots standing above the coal, 

 he explains by reference to similar phsenomena in peat marslies, in 

 which the bases of the trunks of ancient forest trees stand with the 

 roots exposed, owing to the shrinking of the surrounding peat. 



3. In discussing the third point, that the trees became hollow 

 from the decay of their wood, and were filled with sedimentary 

 matter after their immersion, Mr. Bowman refers to the facts re- 

 corded in the preceding paper by Mr. HawkshaAV (see vol.xvii. p. 541); 

 and in confirmation of them states, that Mr. Schomburgk during his 

 four years' travels in Surinam repeatedly observed similar phseno- 

 mena. Mr. Bowman then proceeds to explain the processes by which 

 he conceives the fossil trees were gradually submerged — their upper 

 branches torn off" — their interior removed by natural decay, — their 

 bark converted into coal, — their central cavities filled with sediment; 

 and the whole buried beneath the stratum of shale or sandstone in 

 W'hich the trees were discovered. He afterwards applies the phse- 

 nomena which he believes these processes produced to the condition 

 and position of the trees and the arrangement of the surrounding 

 sedimentary matter. The author then enters into the inquiries, 1st, 

 the time Avhich the trees may have required to attain their dimen- 

 sions ; and consequently the minimum of years requisite for the accu- 



