470 ERECT POSITION OF FOSSIL TREES. 
sea shore, or by inland sections of quarries, banks 
of rivers, &c.* 
The vertical position of these trunks, however, 
is only occasional and accidental ; they lie in- 
clined at all degrees throughout all the strata of 
the carboniferous series ; but are most frequently 
prostrate, and parallel to the lines of stratification, 
and, in this position are usually compressed. 
When erect, or highly inclined, they retain 
their natural shape, and their interior is filled 
with sand or clay, often different from that of 
the stratum in which their lower parts are fixed, 
and mixed with small fragments of various other 
plants. As this foreign matter has thus entirely 
* On the coast of Northumberland, at Creswell hall, and 
Newbiggin, near Morpeth, many stems of Sigillaria may be seen, 
standing erect at right angles to the planes of alternating strata 
of shale and sand-stone ; they vary from ten to twenty feet in 
height, and from one to three feet in diameter, and are usually 
truncated at their upper end ; many terminate downwards in a 
bulb-shaped enlargement, near the commencement of the roots, 
but no roots remain attached to any of them. Mr. W. C. Tre- 
velyan counted twenty portions of such Trees, within the length 
of half a mile ; all but four or five of these were upright ; the 
bark, which was seen when they were first uncovered, but soon 
fell off, was about half an inch in thickness, and entirely con- 
verted into coal. Mr. Trevelyan observed four varieties of these 
stems, and engraved a sketch of one of them in 1816, which is 
copied in Count Sternberg's Tab. 7, Fig. 5. 
In September, 1834, I saw in one of the Coal Mines of Earl 
Fitzwilliam, at Elsecar, near Rotherham, many large Trunks of 
Sigillaria, in the sides of a gallery by which you walk into the 
mine, from the outcrop of a bed of Coal about six feet thick. 
These stems were inclined in all directions, and some of them 
