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which lies in the middle region of that large, and widely extended series of Sandstones, and Conglomerates, Limestones, and Marl, which English Geologists have usually designated by the common appellation of the New red Sandstone Group, including all the strata that are interposed between the Coal formation, and the Lias.
M. Brongniart, in his Terrain de l’Ecorce du Globe, 1829, has applied to this middle division the very appropriate name of Terrain Paecilien, (from the Greek roixàog), a term equivalent to the names Bunter Sandstein, and Grès bigarré, which it bears in Germany and France; and indicating the same strata which, in England, we call the new Red Sandstone. (See Plate 1. Section No. 17.)
Mr. Conybeare, in his Report on Geology to the British Association at Oxford, 1832 (Page 379, and P. 405, Note,) has proposed to extend the term Paecilitic to the entire Group of strata between the Coal formation and the Lias; including the five formations designated in our section (Pl. 1, No. 15, 16, 17, 18, 19) by the names of New Red Conglomerate, Magnesian Limestone, Variegated Sandstone, Shell Limestone, and Variegated Marl. Some common appellative for all these formations has been long a desideratum in Geology; but the word Paecilitic is in sound so like to Pisolite, that it may be better to adhere more literally to the Greek root roixàog, and apply the common name of Poikilitic group to the strata in question.*
* The general reception of such a common name for all these strata, and the reception of the Grauwacké series into the Cambrian and Salurian systems, as proposed by Professor Sedgwick and Mr. Murchison, will afford three nearly equal and most convenient groups or systems, into which the strata composing the Transition and Secondary series may respectively be divided; the former comprehending the Cambrian, Salurian, and Carboniferous systems, and the latter comprehending the Poikilitic, Oolitic, and Cretaceous Groups.
Ornithichnites, or foot-marks of several extinct species of birds, found in the New Red sandstone of the Valley of the Connecticut.” (Hitchcock.)
* In the American Journal of Science and Arts, January, 1836. V. XXIX. No. 2. Professor Hitchcock has published a most interesting account of his recent discovery of Ornithichnites, or foot-marks of birds in the New Red sandstone of the valley of the Connecticut. These tracks have been found at various depths beneath the actual surface, in quarries of laminated flag-stones, at five places near the banks of this river, within a distance of thirty-miles. The sandstone is inclined from 5°, to 30°, and the Tracks appear to have been made on it before the strata received their inclination. Seven of these tracks occur in three or four quarries within the space of a few rods square; they are so distinct that he considers them to have been made by as many different species, if not genera, of birds. (See Pl. 26a. Figs. 1–14. The footsteps appear in regular succession, on the continuous track of an animal in the act of walking or running, with the right and left foot always in their relative places. The distance of the intervals between each footstep on the same track is occasionally varied, but to no greater amount than may be explained by the Bird having altered its pace. Many tracks of dif. ferent individuals and different species are often found crossing one another; they are sometimes crowded like impressions of feet on the muddy shores of a stream, or pond, where Ducks and Geese resort. (See Pl. 26a. Figs. 12. 13. 14.) None of the footsteps appear to be those of Web-footed Birds; they most nearly resemble those of Grallae, (Waders) or birds whose habits resemble those of Grallae. The impressions of three toes are usually distinct, except in a few instances; that of the fourth or hind toe is mostly wanting, as in the footsteps of modern Grallae. The most remarkable among these footsteps are those of a gigantic bird, twice the size of an Ostrich, whose foot measured fifteen inches in length, exclusive of the largest claw, which measured two inches. All the three toes were broad and thick. (Pl. 26a. Fig. 1. and Pl. 26b. Fig. 1.) These largest footsteps have as yet been found in one quarry only, at Mount Tom near Northampton; here, four nearly parallel tracks of this kind were discovered, and in one of them six footsteps appeared in regular succession, at the distance of
The fossil tracks on this Plate are all nearly on the same scale: viz. one-twenty-fourth. The recent footsteps are on a larger scale.
four feet from one another. In others the distance varied from four to six feet; the latter was probably the longest step of this gigantic bird while running. o Next in size to these are the footsteps of another enormous bird (Pl. 26a. Fig. 4.) having three toes of a more slender character, measuring from fifteen to sixteen inches long, exclusive of a remarkable appendage extending backwards from the heel eight or nine inches, and apparently intended, like a snow-shoe to sustain the weight of a heavy animal walking on a soft bottom. (See Pl. 26b. Fig. 2.) The impressions of this appendage resemble those of wiry feathers, or coarse bristles, which seem to have sunk into the mud and sand nearly an inch deep; the toes had sunk much deeper, and round their impressions the mud was raised into a ridge several inches high, like that around the track of an Elephant in Clay. The length of the step of this Bird appears to have been sometimes six feet. On the other tracks the steps are shorter, and the smallest impression indicates a foot but one inch long, with a step of from three to five inches. (Pl. 26a. 2. 3. 5–14. In every track the length of the step increases with the size of the foot, and is much longer in proportion than the steps of any existing species of birds; hence it is inferred that these ancient birds had a greater length of leg than even modern Grallae. The steps at four feet asunder probably indicate a leg of six feet long. In the African Ostrich, which weighs 100lbs., and is nine feet high, the length of the leg is about four feet, and that of the foot ten inches. All these tracks appear to have been made on the Margin of shallow water that was subject to changes of level, and in which sediments of sand and mud were alternately deposited, and the length of leg, which must be inferred from the distance of the footsteps from each other, was well adapted for wading in such situations. No Traces of any Bones but those of fishes (Palaeothrissum) have yet been found in the rock containing these footsteps, which are of the highest interest to the Palaeonthologist, as they establish the new fact of the existence of Birds at the early epoch of the New Red sandstone formation; and further show that some of the most ancient forms of this class attained a size, far exceeding that of the largest among the feathered inhabitants of the present world, and were adapted for wading and running, rather than for flight.
EXPLANATION OF PLATE 26*. - 41
Fig. 1. Ornithichnites giganteus. Many tracks of this
species occur at Mount Tom, near Northampton,
Figs. 12. 13. 14. O. diversus; from the Horse Race
Quarry. Tracks of different individuals of different
Fig. 16. Recent track of a Pea-hen.
Fig. 1. Ornithichnites giganteus. The natural cast here figured represents the form and size of the foot, and part of the claws. (Hitchcock.)
Fig. 2. Ornithichnites diversus, with impressions of the appendage to the heel, drawn from a plaster mould sent by Prof. Hitchcock to the Geol. Soc. of London. (Original.)
Fig. 3. Track of a small animal on Oolitic slate near Bath. See Journal of Royal Institution of London, 1831, p. 538, Pl. 5. (Poulett Scrope.)"
PLATE 27. V. I. p. 205.
Figs. 1–8. Tubercles and Scales, illustrating the four new Orders of Fishes, established by Professor Agassiz. (Agassiz.)
* Mr. Poulett Scrope has presented to the Geol. Soc. of London a series of Slabs selected from the tile quarries worked in the Forest Marble beds of the Oolite formation near Bradford and Bath. The surface of these beds is covered with small undulations or ripple markings, such as are common on the sand of every shallow shore, and also with numerous tracks of small animals (apparently Crustaceans) which traversed the sand in various directions, whilst it was yet soft, and covered with a thin film of clay. These footmarks are in double lines parallel to each other, showing two indentations, as if formed by small claws, and sometimes traces of a third claw. (See Pl. 26°, Fig. 3.) There is often also a third line of tracks between the other two, as if produced by the tail or stomach of the animal touching the ground. Where the animal passed over the ridges of the ripple markings or wrinkles on the sand, they are flattened and brushed down. Thus a ridge between b. and d. (Pl. 26", Fig. 3) has been flattened, and there is a hollow at e. on the steep side of the ridge, which may have been produced by the animal slipping down or climbing up the acclivity.