Extraneous FOSSILS. 639
are frequently also met with nearer the surface; in many parts of the isle of Ely, and sonear us as about Windsor, in the bogs there is great plenty of oaks ; sometimes wholetrees are discovered, and the wood is little inferior in hardness to that of the most solidfresh tree.
The fossile trees are usually found without their roots, tho’ these very roots, and eventhe leaves and fruit are often found in the fame earth at some distance, many of thetrees are broken off near the root; these lye horizontally, and have many of their largerbranches also sever’d from them, and found at small distances ; the extremities of theboughs are fefually broken off, and where the roots lye in an irregular position, theirextremities are usually- broken off also; but these more frequently stand in their naturalposture erect, and with their large roots running in their natural direction down intothe clay, or other firmer bottom of the bog, and not unfrequently the stumps of theseappear above the surface, the trunks lying at some small distance.
’Tis idle to imagine that these have been buried either at the creation, or the generaldeluge ; at the first of those times the strata must have been form’d before trees wereyet in being, and the peat wood in particular is so far from being of Diluvian date, thatmuch of it has been growing within this three or four hundred years in the very placeswhere it is now buried ; in this state, that is, little alter’d from their natural condition itis, that we principally find the fruits and larger parts of trees.
What we find of them more alter’d, are sometimes large and long branches of trees,sometimes shorter, sometimes small fragments of branches, and most frequently shape-less pieces of wood.
The larger and longer branches are usually found bedded in the strata of stone, andthese are usually more or less alter’d into the nature of the stratum they lie in.
The shorter and smaller branches are found in vast variety in the strata of blue clay,of which they make tiles in the neighbourhood of London; these usually carry the wholeexternal resemblance of what they once were, but nothing of the inner structure, havingall their pores so filled up with the matter of the common vitriolick Pyrites as to seempure masses of that matter; these fall to pieces on being expos’d to a moist air,and are what are principally used for the making green vitriol or copperas.
The irregular masses or fragments of wood are principally of oak, and are found a-mong gravel, and in many other strata these are variousty altered by the insinuation ofcrystalline, and stony particles, but still preserving the veins of wood, they make abeautiful figure when polistt’d.
These, according to the various matter that has fill’d their pores, assume various co-lours, and the appearance of various Fossils that have filled them, some are perfectlywhite, and but moderately hard, others of a brownish black, or perfectly black, and muchharder; others of a reddish black, others are yellowish, and others greyish, and othersof a ferrugineous colour ; they are of different weights and hardnesses according to thenature or quantity of the stony particles they contain; the most singular of these that I havemet with, are two in my own possession, the one with its pores filled every where witha pure pellucid Crystal, the other a black mass which was simple oak within this hun-dred years, having been put as a prop to a roof of one of the mines in the Hartz forest,yet now is so perfectly petrify’d as to strike fire with steel; this is much of thesame kind with the famous Fossil wood, of the Lough Neagh in Ireland, whichthe ingenious Mr. Simon has taken great pains to prove of recent petrefaction ; and thisis a plain evidence of the possibility of that being the case. Mr. Simon has made manyaccurate experiments to prove this, and has favoured me with large quantities of thewood, some of which is wholly, some only a part petrify’d. In the specimens I havefrom Germany, some have veins of sparry, some of earthy, and some of matter resem-bling that of the common pebbles; these sometimes, tho’ rarely, have the shape of parts ofbranches of trees, they more usually look like broken pieces of boards, and are generallyfound capable of a high polish.
Many substances have, it is certain, been preserv’d in the cabinets of the curious forpetrify’d wood, which have very little right to that name; but where the fibrose andfistular texture of the striæ, and the vestiges of the Utriculi and Tracheae or air vessels, areyet remaining, the bark yet perfect, and the several circles yet visible, which denotedthe several years growth of the tree, none can deny such substances to be real foffilewood ; and such as these are often cover’d with efflorescences of Spar or other minerals,and frequently contain veins of pure Spar or Crystal.
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