PEAT.—LIGNITE.— BROWN COAL. 71 
the bodies of the primitive hunters, wrapped in skins, have 
been discovered. 
In Belfast Lough, a bed of peat is situated beneath 
the ordinary level of the waters, but is generally left bare 
at the ebb tides. Trunks and branches of trees, with vast 
quantities of hazel nuts, are imbedded in the peat; the 
whole being covered by layers of sand, and blue clay, or 
silt. In most cases the pericarps of the nuts are empty, 
the kernels having perished; but on the eastern side of 
the Lough, which is bounded by limestone rocks, they 
contain calc-spar, which in some examples forms a lining of 
delicate crystals (Plate V. fig. 6); while in others the kernel 
is transmuted into calcareous spar (see Plate III. fig. 7); 
but the pericarps are unchanged, and in the state of common 
dried nut-shells; the water which deposited the spar in 
their cavities not having left a particle of mineral matter in 
the ligneous substance through which it had filtrated. 
In a subterranean forest at Ferry-bridge, Yorkshire, hazel 
nuts in a similar mineralized state occur, and the branches 
and stems of the trees have undergone a like change; the 
central ligneous axis is petrified, while the outer zones have 
undergone no lapidification, but remain in the state of dry 
rotten wood.* 
LienitE, Brown Coat, or CANNEL Coat; these are terms 
employed to designate certain varieties of carbonized wood, 
in which the ligneous structure is more or less distinctly 
preserved. ignite may be regarded as an imperfect coal, 
for in its chemical properties it holds an intermediate place 
between peat and bituminous coal. It is for the most part 
found in tertiary formations, but is not unfrequent in 
ancient secondary deposits, and may occur in the earliest 
sedimentary rocks which contain vegetable remains. 
The newer deposits of Brown or wood-coal, are commonly 
* Specimens are preserved in the Museum at York. 
