seemed a novelty to us after the eye had dwelt for so many hundreds of miles on native forests and new clearings. The streets of Philadelphia rival the finest Dutch towns in cleanliness, and the beautiful avenues of various kinds of trees afford a most welcome shade in summer. We were five days here, and every night there was an alarm of fire, usually a false one; but the noise of the firemen was tremendous. At the head of the procession came a runner blowing a horn with a deep unearthly sound, next a long team of men (for no horses are employed) drawing a strong rope to which the ponderous engine was attached with a large bell at the top, ringing all the way; next followed a mob, some with torches, others shouting loudly; and before they were half out of hearing, another engine follows with a like escort; the whole affair resembling a scene in Der Freischutz or Robert le Diable, rather than an act in real life. It is, however, no sham, for these young men are ready to risk their lives in extinguishing a fire; and as an apology for their disturbing the peace of the city when there was no cause, we were told "that the youth here require excitement!" They manage these matters as effectively at Boston without turmoil.

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62

EXCURSION TO NEW JERSEY.

CHAP. IV.

CHAPTER IV.

Excursion to New Jersey-Cretaceous Rocks compared to European. -General Analogy of Fossils, and Distinctness of Species.-Tour to the Anthracite Region of the Alleghanies in Pennsylvania.— Long parallel Ridges and Valleys of these Mountains.-Pottsville. -Absence of Smoke.-Fossil Plants same as in Bituminous Coal. -Stigmaria.-Great Thickness of Strata.-Origin of Anthracite. -Vast Area of the Appalachian Coal-field.-Progressive Debituminization of Coal from West to East.-General Remarks on the different Groups of Rocks between the Atlantic and the Mississippi.-Law of Structure of the Appalachian Chain discovered by the Professors Rogers.-Increased Folding and Dislocation of Strata on the South-eastern Flank of the Appalachians.—Theory of the Origin of this Mountain Chain.

CRETACEOUS STRATA OF NEW JERSEY.

Sept. 30, 1841.-FROM Philadelphia I made a geological excursion of several days, to examine the cretaceous strata of New Jersey, in company with Mr. Conrad, to whom we are indebted for several valuable works on the fossil shells of the tertiary, cretaceous, and Silurian strata of the United States. We went first to Bristol on the Delaware to visit Mr. Vanuxem, then engaged in preparing for publication his portion of the State Survey of New York; next by Bordentown to New Egypt, and returned by the Timber Creek, recrossing the Delaware at Camden.

Although in this part of New Jersey there is no white chalk with flints, so characteristic of rocks of this age in Europe, it is still impossible to glance at the fossils, and not to be convinced that Dr. Morton was right

in referring in 1834 the New Jersey deposits to the European cretaceous era. He and Mr. Conrad remarked that the American species of shells were nearly all new, or distinct from those before described, and yet very analogous to those of cretaceous strata already known. The New Jersey rocks have been separated into five subdivisions, but of these two only have proved sufficiently rich in organic remains to admit of their being compared with corresponding strata in distant regions. The lower of these consists in great part of green sand and green marl, and was supposed by Dr. Morton to be the equivalent of the English "Green sand;" while an upper or calcareous rock, composed chiefly of a soft straw-coloured limestone with corals, was thought to correspond with the white chalk of Europe. But after carefully comparing my collection, comprising about 60 species of shells, besides many corals and other remains, I have arrived at the conclusion that the whole of the New Jersey series agrees in its chronological relations with the European white chalk, or, to speak more precisely, with the formations ranging from the Gault to the Maestricht beds inclusive. Among the shells, in determining which I have been assisted by Professor E. Forbes, not more than four out of sixty seem to be quite identical with European species. These are Belemnites mucronatus, Pecten quinquecostatus, Ostrea falcata (O. larva, Goldfuss), and O. vesicularis. Several others, however, approach very near to, and may be the same as European shells, as for example Trigonia thoracica, and at least fifteen may be regarded as good geographical representatives of well-known chalk fossils, belonging, for the most part, to beds above the Gault

64

GENERAL ANALOGY OF FOSSILS.

СНАР. IV.

in Europe. There are a few very peculiar forms among the American testacea, such as Terebratula Sayii (Morton).

In the upper or straw-coloured limestone, I found, on the banks of the Timber Creek, twelve miles southeast of Philadelphia, six species of corals and several echinoderms, chiefly allied to Upper Cretaceous forms. The same calcareous stratum also abounds in foraminifera, characteristic of the chalk, comprising, among others, the genera Cristellaria, Rotalina, and Nodosaria. Mr. Owen has recognised, in the fossil reptiles from New Jersey, not only the vertebræ of Mosasaurus, previously noticed by Dr. Morton, but also the Pliosaurus, and a large crocodile of the Procœlian division, or having its vertebræ like the living species, with the anterior surface concave. There are also many fish of the shark family, analogous to those of the English chalk, and the Galeus pristodontus is represented by a species very closely allied, if not identical.

Upon the whole, the list of genera, and the forms of the species, are remarkably analogous to the cretaceous group of Europe; and the agreement of four or five species of Mollusca, being in the proportion of about seven in the hundred, implies no inconsiderable amount of affinity at a distance of between 3000 and 4000 miles from the corresponding assemblage of fossils in Central and Northern Europe, especially when we recollect that there is a difference in latitude of more than ten degrees between the two districts compared. Some of the species common to the opposite sides of the Atlantic, are those which in Europe have the greatest vertical range, as Pecten quinquecostatus,

and which might therefore be expected to recur in distant parts of the globe.

At the same time we learn from the facts above mentioned, that the marine fauna, whether vertebrate or invertebrate, testaceous or zoophytic, was divided at the remote epoch under consideration, as it is now, into distinct geographical provinces, although the geologist may everywhere recognise the cretaceous type, whether in Europe or America, and I might add, India. This peculiar type exhibits the preponderating influence of a vast combination of circumstances, prevailing at one period throughout the globe-circumstances dependent on the state of the physical geography, climate, and the organic world in the period immediately preceding, together with a variety of other conditions too long to enumerate here. It would not be difficult for a naturalist to point out the characters stamped on the living Flora and Fauna, by which they also might be distinguished as a whole from those of all former geological epochs. The resemblance of the corals, shells, and insects, of certain temperate regions of the southern hemisphere (Van Dieman's Land, for example), to those of the temperate zone north of the equator, or the close analogy of the arctic and antarctic fauna, the species in both cases being quite different, are illustrations of the common type here alluded to, which is evidently caused or controlled by some general law, and by some mutual relation existing between the animate creation and the state of the habitable surface at any given period.

ANTHRACITE FORMATION OF PENNSYLVANIA.

Oct. 3. Having already seen the carboniferous stra