408 Geological Observations made at Ferrybridge, tyc. 



carbonate of lime. Usually the central portion is lapidified, 

 while the outward layers are unchanged : but sometimes the 

 whole mass of wood is filled with stony particles, while the 

 bark remains soft and pliable. One specimen shows the cen- 

 tral wood petrified, the external layers decayed away, and the 

 bark externally coated with pyritous carbonate of lime. Blue 

 phosphate of iron, so common in alluvial deposits, colours some 

 of the fragments of wood. The bark and soft wood and nut- 

 shells burn with a brilliant and continued light; even the fi- 

 brous stony substance emits a faint lambent flame. 



Boiies. — The lower jaw of a deer, about the size of the red 

 deer, coloured by phosphate of iron. — Upper part of the tibia 

 of an ox, in the sinuosities of which a hazel root has struck its 

 branches, and over whose surface a pyritous layer is spread, like 

 that which invests the bark of the specimen of wood already 

 mentioned. 



No other example has occurred to me of petrified nuts or 

 wood in Yorkshire; and the cause of the peculiarity in this 

 instance is not difficult of discovery. At Knottingley the ve- 

 getable relics were buried so near to the limestone rock that 

 its calcareous springs obtained access, and in a long succession 

 of years filled the interstices of the plants with a stony de- 

 posit. It is remarkable that the interior parts of the branches 

 are often hardened to stone, while the bark and external layers 

 of wood are not perceptibly altered; and that in the same 

 manner the kernel of a nut should have become a mass of calc 

 spar, while its shell has remained without any change of sub- 

 stance. 



Except in the peculiar and interesting circumstance of the 

 vegetable remains having become lapidified, little essential 

 difference appears between this freshwater deposit and those 

 in Holderness, which will be minutely described in my forth- 

 coming publication on the Geology of the Yorkshire Coast; 

 and in each case their high antiquity is proved by the deep 

 sediment laid upon them. This sediment itself is of varying 

 antiquity. It may conceal the most ancient and the most 

 recent of the works of man; — a boat used in some distant 

 ages of the world, as in Romney Marsh ; or an English oar, 

 coin, and horse shoe, as in part of the excavation at Knot- 

 tingley. 



York, Nov. 3, 1828. 



Reference to Plate II. 

 Fig. 1. A section representing the general appearance of quar- 

 ries at Brotherton. 

 (a). The limestone rock, with straight fissures (b) and 



