﻿118 Notice of Dr. MantelVs Medals of Creation. 



in the cliffs of alum shale on the coast of Yorkshire. The stump 

 of a tree in a cliff, three feet in diameter by fifteen long, was 

 found to be jet in the roots, which were encased in shale, while 

 the trunk, being in sandstone, was silicified, and part of the 

 wood was in decay, having escaped the mineralizing process. 

 Vegetable remains enclosed between beds of clay are peculiarly 

 prone to be converted into coal — the gaseous elements being im- 

 prisoned by the tenacious investing substances. Dr. Mantell 

 fully sustains the theory of the vegetable origin of coal, which 

 indeed no thorough student of the facts ought to doubt. 



" It is estimated that scarcely one thousand species of plants 

 have been discovered in a fossil state, while the known recent 

 species amount to nearly one hundred thousand. 3 ' Confervites^ 

 which are cellular and aquatic plants, " are found sometimes in 

 transparent quartz pebbles."* 



Some of the fossilized Calamites (resembling horse or mare's 

 tails) are from one foot to three feet in diameter ; they were very 

 numerous in the coal formation. The largest species of modern 

 British ferns scarcely exceed four or five feet in height, but the 

 tree ferns of warm climates are sometimes thirty to forty feet 

 high, thus resembling the ferns of the coal period. There are 

 more than 2000 species of living ferns, while those hitherto 

 found in the fossil state exceed 150. Of the Pecopteris or em- 

 broidered fern, the most abundant fern in coal, leaves have been 

 found 4 feet wide, and of a proportionate length. 



A few years since, in forming the Bolton and Manchester rail- 

 way, five stems or trunks of Sigillarias were found standing as 

 they grew, the largest 11 feet high and 7£ in circumference at 

 the base. In Derbyshire in 1838, in forming a railway five miles 

 from Chesterfield, they encountered a grove of nearly 40 Sigil- 

 lariae, standing not more than 3 or 4 feet apart and at right an- 

 gles to the strata. In Nova Scotia, on the southern shore of the 

 Bay of Fundy, in cliffs about 2000 feet high of the coal forma- 

 tion, are ten rows of trees, (Sigillariae,) one row above another, 

 proving as many distinct surfaces of the ground, and as many 

 submergences.* 



Sigillariae vary from a few inches to 5 feet in diameter, and 

 from 5 to 50 feet in height. The Sigillariae in the opinion of 



* Mr. Lyell, in this Journal, Vol. xlv ? p. 353. 



