Since some pages of your valuable magazine are occasionally devoted to the description and illustration of “Gems from Private Collections,” allow me to offer a drawing and some observations on Spirifera convoluta, Phillips, one of the most remarkable of our British carboniferous spirifera, and which will serve at the same time as a small supplement to the paper I published in the eleventh number of The Geologist.

At page 35 of my “Monograph” I described Sp. convoluta as a distinct species, but subsequently I thought that it might, perhaps, be a very transverse or exceptional condition or variety of Sp. bisulscata, Sowerby.

Experience teaches us that individuals of the same species may assume great differences in shape; that a Spirifera, for example, which in its normal condition is about as wide as long, may at times exceed these proportions very considerably in one or the other direction, and that we are often too prone to seize upon similar variations as pretexts for the creation of so termed species.

In June, 1827, Dr. W. H. Fitton read before the Geological Society of London the following statement:—“It is obvious that, during a period of time sufficient for the accumulation of the Wealden, the deposition of matter in the adjacent seas could not have been inconsiderable; so that we might expect to find, interposed between the strata which then formed the bottom of the sea and the Lower Greensand, a series of beds coeval with the Wealden in point of date, but differing from it in possessing the characters of a marine deposit, and including marine shells and other productions of salt water; with which, near the shore, the productions of the land, or even the freshwater shells of the rivers, might be occasionally intermixed.…. 1st. That the Wealden and its marine equivalent could not both be found in the same place; and consequently (since we have the former in England) that the marine beds of that date are not to be expected generally in this country; 2dly.

Those marked with an asterisk (*) are minerals,—that is, occur naturally; those with a double asterisk (**), abundantly. The others form the chemical constituents of minerals, but are not minerals themselves.

Carbonic and the Sulphuric acids also occur naturally in volcanic regions, in the form of gases. Lime, Magnesia, and Baryta are also called Alcaline Earths.

XIV. Of the elementary bodies it therefore appears that only two —carbon and sulphur—are found as minerals in any considerable quantity. In composition they are unimportant in rocks, except in the binary compounds given.

A section along the coast from Ebbs Nook to Annstead Bay, of nearly one and a half miles in length, exhibits a fine series of rocks belonging to the Mountain Limestone Formation. Thick sandstones and limestones, shales with ironstone, and coal-seams are intercalated with each other; and these strata are traversed by a lead-vein and a basaltic dyke. As we wander along the shore, we meet with evidences of sea-deposits in the limestones and calcareous shales, wherein are embedded many corals and mollusks; the sandstones, shales, and coal afford relics of the vegetation of the Carboniferous Era; some slaty sandstones give distinct indications of ancient shallow seas and coast-lines, whereon the waves broke gently and over which worms crawled; while the basaltic dyke tells of the play of internal forces, rending asunder the vast mass of stratified rocks, and pouring molten lava into the fissures.

“There are stranger things” wrote old Aubrey, “than a man sees in a journey between Staines and Windsor.” Doubtless there are, and not the least strange in modern times is the discovery of the works of men's hands in association with the bones of mammoths and other extinct terrestrial beasts, which have always hitherto been supposed to have passed away before the “lord of all he surveys” made his appearance. For years it has been the practice of geologists to ignore any asserted evidence of human remains in the same strata with those of the great extinct mammalia, and certainly, generally speaking, the evidence offered was carelessly got, or only very imperfectly substantiated, so that, in its general weakness and unreliableness there is some justification of the practice. An energetic French antiquary, however, has brought the matter so prominently forward, and substantiated his assertions by discoveries and proofs at once so novel and so convincing, that geologists and antiquaries were both alike compelled to investigate the matter, and neither have hesitated to accept the proofs afforded.

The expression “fossil lightning” may seem somewhat paradoxical, but it is here employed in a figurative sense to designate a condition of things which we have good modern evidence to prove to have been the result of the lightning's flash, myriads of ages gone by. Of late years vitrified sand-tubes have been discovered in Cumberland, in Prussia, South America, Natal, and other places; and these have been very clearly made out as having been directly caused by lightning, and hence they have been called by mineralogists “Fulminary tubes” or Fulgurites. All these would appear, so far as we can ascertain, to have been formed at comparatively a very recent period, and hardly, therefore, deserving of the appellation of “fossil lightning.” Nevertheless, as I have come across some examples of such bodies on the surface of the flagstones which form our pavements, and of the antiquity of which there cannot be any doubt whatever, I have no hesitation in making use of the term which heads this chapter.

Much attention has been excited in France for some few months past by the fall of a large aërolite, which took place in the canton of Montrejeau on the 9th of December last. We have now all the details that we are ever likely to have concerning this remarkable meteor. It fell about seven o'clock in the morning, appearing first in the north-east like a large red-hot bomb, which passed rapidly to the south-west, where it remained stationary for an instant. It then emitted a considerable column of smoke and flame; three seconds after which a loud detonation was heard, followed by a rumbling noise. Although in broad daylight, the little town of Aurignac was completely illuminated by the passage of this aërolite. After the explosion nothing was observed in the sky but a streak of vapour and a small cloud which marked out the direction followed by the meteoric stone, and the place where it exploded. Shortly after this phenomenon two large fragments of the aërolite were picked up in the parishes of Aussan and Clarac; one of these weighed about 90 lbs., and had sunk into the ground for nearly two yards; the other, that fell at Clarac, broke through the roof of a cottage; it weighed from 16 to 20 lbs., and was so hot when first seen that it could not be touched for some time. These blocks present rounded forms, their surface is black and smooth, the interior is formed of a sort of grey substance, not unlike certain volcanic products in structure.

The March number of The Geologist contains, I observe, a notice of the “Upper Ludlow Tilestones,” and the author invites descriptions of their equivalent beds in other districts. Now, so close are the resemblances, lithologically and palæontologically, between these deposits and those of Forfarshire, that they may be regarded as part of one and the same series. I have been induced, therefore, to throw together the following observations upon our northern Scottish system.

The rocks to which I refer occupy a narrow but extended trough-line along the central district of Forfarshire, commencing on the east near Montrose, and terminating at Babruddery and Rossie Den on the west. They trend in a south-westerly direction, across the river Tay, into Fifeshire at Parkhill, Newburgh, and along the northern slope of the Ochils towards Dunning and Tereagles in Perthshire. These tilestones, and the grey and red sandstones with which they are systematically associated, occupy the whole superficies of that well-known and beautiful tract of country which is bounded by the old crystalline rocks of the Grampians on the north, and by the later felspathio Ochil range on the south; and it includes the celebrated geological localities of Cavonylie, Glammis, Forfar, Kinnordie, Clashbennie, Babruddery, and Parkhill.

For some years past it has been a commonly received doctrine among continental geologists that lava-streams could not consolidate on slopes or declivities of more than five degrees. When, then, solid lavas were found in various volcanic mountains at high angles, other sources of origin than the mere outflow from their respective craters had to be sought; and thus arose the theoretical idea of the formation of the cone or crater at a late period of the volcano's existence—after for ages numerous lava-streams had issued from it and had become consolidated one over the other into stony beds on successive flat plains—by the uprise and bursting of a vast dome or bubble; and such was called a “crater of elevation”.

The lowest beds of Speeton Clay in overlying contact with any inferior stratum have never been found in Filey Bay, but a little to the south of a point where it is first exposed Lias “scars” exist with Ammonites communis and A. Walcotti in situ, showing great upheaval or disturbance, or else great unconformability here.

1. The lowest known beds of Speeton Clay, so called, consist of blue clay, with seams of septarian nodules. In one of these seams, in beds of a black claystone, specimens of Ammonites biplex three to four inches in diameter are not unfrequent. This is the only fossil found in this bed.