Petrifactions. MIN ERA L O G Y. Petrifactions. 
at prefent. The mountain on which this interefting dif- 
covery was made, is that of Lans, in the canton of Oiians. 
The trees found there are, mountain-alh, birch, and the 
common larch. The roots and part of the trunks can be 
plainly diftinguilhed. The laft of thefe trees does not 
grow at prefent in the neighbourhood. The author of 
this memoir afcribes the greater degree of cold, which 
now prevails on thefe mountains, to two principal caufes : 
firft, the valleys becoming deeper, which has changed the 
elevation of the fummits in regard to their bafes and the 
furrounding countries; the fecond is the deftruftion of 
the ancient forefts, which had gradually extended them- 
felves to great heights, but which, when once deitroyed, 
cannot grow up again at the fame heights, becaufe the 
trees are deprived of that mutual Ihelter which they af¬ 
forded to each other. Phil. Mag-, vol. v. 
ee. Filices, or ferns. Various genera and fpecies of 
ferns, as Equifetum, Ofmundia, Achrofticum, Pteris, Al- 
plenium, Polypodium, Adiantum, &c. occur in fhiftole 
and bituminous marl and alumine covering veins of coal, 
in fandflone and other foffils, in very numerous varieties, 
in many parts of Great Britain, France, Germany, Italy, 
Bohemia, Saxony, and moll parts of Europe. 
SS. Mufcorum. Various mofles and fea-weeds ; in Ve¬ 
nice, Saxony, and Silefia. 
2. Phytolithus rhizolithus ; the roots of vegetables. 
Thefe are molt commonly found under-ground in a ftate 
of decay, fometimes hollow or filled with other foffil fub- 
ftances, fometimes covered with a ftony cruft; though 
fometimes they occur petrified in France, Italy, Hungary, 
Bohemia, Sweden, Siberia, Germany, &c. 
3. Phytolithus trunci; the trunk or ftalk of vegetables. 
The trunks »f trees are found in almoft every part of the 
globe, and in various ftates of decay and appearance; 
fometimes forming fubterraneous woods, the pieces of 
which are found or carious, or perforated by the Teredo. 
Numerous fpecimens of thefe were dug up in forming 
the Highgate-archway. Some are in a complete foffil ftate, 
and will admit of a high polifh : others are converted into 
charcoal, with or without the bark, and often fo perfeCt 
as to diftinguifh the kind, as oak, afh, fir, &c. Some of 
them are marmoreous, and often filled with fpar: of thefe, 
fpecimens are met with in Ireland, and many parts of 
Germany : fome in gypfum, fome in flint, fome in agate : 
thefe laft are found in Siberia, Hungary, and Saxony, 
more or lefs opaque, breaking into coarfe fplinters or in¬ 
determinate fragments, a little filming, taking a fine po¬ 
lifh, fibrous internally, of a conchoidal texture, variegated, 
fpotted or ftriate, blackifh or of a fmoke-colour, fometimes 
red, ocliraceous, or green: fome are found in opal, in Upper 
Hungary, hardifh, opaque or nearly fo, breaking into in¬ 
determinate fragments or long fplinters, l’eparating into 
crufts, generally a little fhining, moftly variegated with 
white, greyilh-brown, or ocliraceous and hyacinthine al¬ 
ternate ftreaks : fome of thefe fpecimens are bituminous, 
which are found frequently forming entire fubterraneous 
woods in various parts of England and Ireland, particu¬ 
larly in Lincolnfhire : alfo in almoft all the countries on 
the continent of Europe: in Pruffia they are found in 
ftrata that are fuperincumbent on amber. 
There are many places where wood will not grow at 
prefent, where yet the moifes are well flocked with this 
under-ground timber; but yet it appears there muff have 
been woods formerly there; elfe how came they in the 
mofl'es ? To prove this, the earl of Cromartie (Phil. Tranf. 
N° 275.) gives 11s the hiftory and origin of a mofs, in 
great meal'ure from his own experience. In the parifh of 
Lochburn, in the year 1651, he law, near the top of a very 
high hill, a plain about a mile over, then covered with a 
firm Handing w r ood, but which was fo very old, that not 
only the trees had no leaves or bark on, but the outlide, 
for the fipace of an inch inwards, was dead white timber, 
though within they were firm. Coming by the place fif¬ 
teen years after, he could not difcover the leaft appearance 
of a tree; but, inftead thereof, there was a plain green 
Vo h. XV. No- J063. 
533 
ground covered with a mofs; the trees being all fallen, 
and having lain fo thick over one another, that the green 
had over-run the whole timber, by means of the moTliure 
draining from the hill above it, and ftagnating on the 
plain. He adds, that none could pafs over it, the fcurf 
not being firm enough to fupport them. In thirty years 
more he found this whole piece of ground turned into a 
common peat-mofs, and the country people digging turf 
and peat there. This accounts for the generation of 
modes, and whence it is that many of them are fumiflied 
with timber. 
It appears, then, that all the trees which we find in 
this foffil ftate, originally grew in the very places where 
we now find them, and have only been thrown down and 
buried there, not brought from elfewhere. It may appear 
indeed an objeftion to this opinion, that moil of the foffil 
trees difeovered in England are of the Pin us or fir kind ; 
and that Csefar fays, exprefsly, that no firs grew in Bri-' 
tain in his time. But this is eafily anfwered by obferv- 
ing, that thefe trees, though of the fir kind, yet are not 
the fpecies ufually called the fir, but the pitch-tree ; and 
Caefar has no-where faid that pitch-trees did not grow in 
England. Norway and Sweden yet, abound with thefe 
trees; and there are at this time whole forefts of them in 
many parts of Scotland, and a large number of them wild 
upon a hill at Wareton in Staffordfhire, to this day. 
In Hatfield-marfh, where fuch valt numbers of the foffil 
trees are now found, there has evidently once been a 
whole foreft of them growing. The laft of thefe was 
found alive and growing in that place within a hundred 
years laft paft, and cut down for fome common ufe. The 
Roman hiftorians tell us, that, when their armies purfued 
the wild Britons, thefe people always fheltered themlelves 
in the miry woods, and low watery forefts. Csefar ex¬ 
prefsly fays this; and obferves, that Caffibelan and his 
Britons, after their defeat, palled the Thames, and fled 
into fuch low morafles and woods, that there was-no pur- 
fuing them; and we find that the Silures fecured them- 
felves in the fame manner when attacked by Oftorius and 
Agricola. The fame thing is recorded of Venutius king 
of the Brigantines, who fled to fecure himfelf in the 
boggy forefts in the midland part of this kingdom; and 
Herodian exprefsly fays, that, in the time of the Romans 
pufhing their conquefts in thefe iflands, it was the cuftora 
of the Britons to fecure theinfelves in the thick forefts 
which grew in their boggy and wet places, and, when op¬ 
portunity offered, to ilfue out thence and fall upon the 
Romans. The confequence of all this was, the deftroy- 
ing all thefe forefts; the Romans finding themlelves fo 
plagued with parties of the natives iffuing out upon them 
at times from thele forefts, that they gave orders for the 
cutting down and deftroying all the forefts in Britain 
which grew on boggy and wet grounds. Thefe orders 
were punctually executed ; and to this it is owing, that 
at this day we can hardly be brought to believe that fuch 
forefts ever grew with us as are now found buried. 
As the Romans were the deftroyers of this great and 
noble foreft, fo they probably were alfo of the feyeral 
other ancient forefts; the ruins of which furnilh us with 
the bog-wood of Staffordlhire, Lancalhire, Yorklhire, and 
other counties. But, as the Romans were not much in 
Wales, in the Ifle of Man, or in Ireland, it is not to be 
fuppoled that forefts cut down by thele people gave ori¬ 
gin to the foffil wood found there ; but, though they did 
not cut down thefe forefts, others did ; and the origin 
of the bog-wood is the fame with them as with us. 
Holinlhed informs us, that Edward I. not being able to 
get at the Wellh, becaule of their hiding themlelves in 
boggy woods, gave orders at length that they lhould be 
deitroyed by fire and by the axe ; and doubtlefs the roots 
and bodies of trees found in Pembrokelhire under-ground, 
are the remains of the execution of this order. The foifil 
wood in the bogs of the Illes of Man and Anglefea, is 
doubtlefs of the fame origin; though we have not any 
accounts extant of the time or occalion of the forefts 
6 U ■ there 
