The World Before the Deluge

• " On the Red Rocks of England,'* by A. C. Ramsay. Quart. Joun Geol.Soc., vol. xxvii.o p. 243.

there without even visiting the sea. And the same is the case in Lake Baikal, in Central Asia. ^

The red colour of the Old Red Sandstone of England and Scotland, and the total absence of fossils, except in the very uppermost beds, are considered by Professor Ramsay to indicate that the strata were deposited in inland waters. These fossils are terrestrial ferns, Adiantites (Pecopteris) Hiberniais, and a fresh-water shell, Anodo7i Jiikesii^ together with the fish Glyptolcpis.^'

The rocks deposited during the Devonian period exhibit some species of animals and plants of a much more complex organisation than those which had previously made their appearance. We have seen, during the Silurian epoch, organisms appearing of very simple type; namely, zoophytes, articulated and molluscous animals, with algae and lycopods, among plants. We shall see, as the globe grows older, that organisation becomes more complex. Vertebrated animals, represented by numerous Fishes, succeed Zoophytes, Trilobites, and Molluscs. Soon afterwards Reptiles appear, then Birds and Mammals; until the time comes when man. His suprem.e and last work, issues from the hands of the Creator, to be king of all the earth — man, who has for the sign of his superiority, intelligence — that celestial gift, the emanation from God. Vast inland seas, or lakes covered with a few islets, form the ideal of the Old Red Sandstone period. Upon the rocks of these islets the mollusca and articulata of the period exhibit themselves, as represented on the opposite page (Plate IX.) Stranded on the shore we, see armour-coated Fishes of strange forms. A group of plants {Asterophyllites) covers one of the islets, associated with plants nearly herbaceous, resembling mosses, though the true mosses did not appear till a much later period. Encriniks and Lituites occupy the rocks in the foreground of the left hand.

The vegetation is still simple in its development, for forest-trees seem altogether wanting. The Asterophyllites, with tall and slender 3tems, rise singly to a considerable height. Cryptogams, of which our mushrooms convey some idea, would form the chief part of this primitive vegetation; but in consequence of the softness of their tissues, their want of consistence, and the absence of much woody fibre, these earlier plants have come down to us only in a fragmentary state. The plants belonging to the Devonian period difier much from

• " On the Red Rocks of England," by A. C. Ramsay. Quart. Jotir. Geo!. Soc, vol. xxvii., p. 247.

1X.—Ideal Landscape of the Devonian Period.

OLD RED SANDSTONE AND DEVONIAN PERIOD. 1 2$

the vegetation of the present day. They resembled both mosses and lycopods, which are fiowerless cryptogamic plants of a low organisation. The Lycopods are herbaceous plants, playing only a secondary part in the vegetation of the globe; but in the earlier ages of organic creation they were the predominant forms in the vegetable kingdom,

I 2 • 3

Fig. 30.— Plants of the Devonian Epoch, i. Algae. 2. Zostera. 3. Psilophyton, natural size.

both as to individual size and the number and variety of their species. In the woodcut (Fig. 30) we have represented three species of aquatic plants belonging to the Devonian period; they are — i, Fucoids (or Algce); 2, Zostera; 3, Psilophyton. The Fucoid closely resembles its modem ally; but with the first indications of terrestrial vegetation we pass from the Thallogens^ to which the Algce belong (plants of simple organisation, without flower or stem), to the Acrogms^ which throw out their leaves and branches at the extremity, and

bear in the axils of their leaves minute circular cases, which form the receptacles of their spore-like seeds. " If we stand," says Hugh Miller, "on the outer edge of one of those iron- bound shores of the Western Highlands, where rock and skerries are ■crowned with sea-weeds; the long cylindrical lines of chorda-filumy many feet in length, lying aslant in the tideway; long shaggy bunches oi Fucus serratus and F. nodosiis drooping "from the sides of the rock; the flat ledges bristling with the stiff cartilaginous many-cleft fronds of at least two species of Chondrus; now, in the thickly-spread Fucoids of this Highland scene we have a not very improbable representation of the Thallogenous vegetation. If we add to this rocky tract, so rich in Fucoids, a submarine meadow of pale shelly sand, •covered by a deep-green swathe of Zostei-cB, with jointed root and slim flowers, unfurnished with petals, it would be more representative still."

Let us now take a glance at the animals belonging to this period.

The class of Fishes seem to have held the first rank and importance in the Old Red Sandstone y«;2/;2^; but their structure was very different from that of existing fishes: they were provided with a :sort of cuirass, and from the nature of the scales were called Ganoid rfishes. Numerous fragments of these curious fishes are now found in geological collections; they are of strange forms, some being completely covered with a cuirass of many pieces, and others furnished with wing-like pectoral fins, as in Pterichthys.

Let any one picture to himself the surprise he would feel should he, on taking his first lesson in geology, and on first breaking a stone — a pebble, for instance, exhibiting every external sign of a waterworn surface — find, to appropriate Archdeacon Paley's illustration, a watch, or any other delicate piece of mechanism, in its centre. Now, this, thirty years ago, is exactly the kind of surprise that Hugh Miller experienced in the sandstone quarry opened in a lofty wall of cliff overhanging the northern shore of the Moray Frith. He had picked up a nodular mass of blue Lias-limestone, which he laid open by a stroke of the hammer, when, behold! an exquisitely shaped Ammonite was displayed before him. It is not surprising that henceforth the half-m.ason, half-sailor, and poet, became a geologist. He sought for information, and found it; he found that the rocks among which he laboured swarmed with the relics of a former age. He pursued his investigations, and found, while working in this zone of strata all around the coast, that a certain class of fossils abounded; but that in a higher zone these familiar forms disappeared, and others made their appearance. He read and learned that in other lands — lands of more recent

OLD RED SANDSTONE AND DEVONIAN PERIOD.

formation — strange forms of animal life had been discovered; forms-which in their turn had disappeared, to be succeeded by others, more in accordance with beings now living. He came to know that he was^ surrounded, in his native mountains, by the sedimentary deposits of other ages; he became alive to the fact that these grand mountaia ranges had been built up grain by grain in the bed of the ocean, and the mountains had been subsequently raised to their present level by

Fig. 31. — Fishes of the Devonian Epoch, i. Coccosteus, one-third natural size. 2. Ptcrichthys, one-fourth natural size. 3. Cephalaspis, one-fourth natural size.

the upheaval of one part of its bed, or by the subsidence of another. The young geologist now ceased to wonder that each bed, or series of beds, should contain in its bosom records of its own epoch; it seemed to him as if it had been the object of the Creator to furnish the inquirer with records of His wisdom and power, which could not be misinterpreted. Among the Fishes of Old Red Sandstone, the Coccostais (Fig. 31, No. i) was only partially cased in a defensive armour; the upper part of the body down to the fins was defended by scales. Pterichthys (No. 2), a

Strange form, with a very small head, furnished with two powerful paddles, or arms, like wings, and a mouth placed far behind the nose, was entirely covered with scales. The Cephalaspis (No. 3), which has a considerable outward resemblance to some fishes of the present time, was nevertheless mail-clad, only on the anterior part of the body.

Other fishes were provided with no such cuirass, properly so called, but were protected by strong resisting scales, enveloping the

Fig. 32. — Fishes of the Devonian epoch, i. Acanthodes. 2. Climatius. 3. Diplacanthus.

whole body. Such were the Acanthodes (i), the Climatius (2), and the Diplacanthus (3), represented in Fig. 32.

Among the organic beings of the Devonian rocks we find wormlike animals, such as the Annelides, protected by an external shell, and which at the present day are probably represented by the Serpula;. Among Crustaceans the Trilobites are still somewhat numerous, especially in the middle rocks of the period. We also find there many different groups of Mollusca, of which the Brachiepoda form more than one-half. We may say of this period that it is the reign

OLD RED SANDSTONE AND DEVONIAN PERIOD.

127

of Brachiopoda; in it they assumed extraordinary forms, and the number of their species was very great. Among the most curious we may instance the enormous Stringocephalus Burtini, Davidsonia Verneuilli, Uncites gryphus, and Calceola Sandalina, shells of singular and fantastic shape, differing entirely from all known forms. Amongst the most characteristic of these Mollusca, Atrypa reticularis (Fig. 33) holds the first rank, with Spirifera concentrica, Leptæna Murchisoni, and Productus subaculeatus. Among the Cephalopoda we have Clymenia Sedgwickii (Fig. 34), including the Goniatites, illustrating

Fig. 33.—Atrypa reticularis.

Fig. 34.—Clymenia Sedgwickii.

the Ammonites, which so distinctly characterise the Secondary epoch, but which were only foreshadowed in the Devonian period.

Among the Radiata of this epoch, the order Crinoidea are abundantly represented. We give as an example Cupressocrinus crassus (Fig. 35). The Encrinites, under which name the whole of these animals are sometimes included, lived attached to rocky places and in deep water, as they now do in the Caribbean sea.

The Encrinites, as we have seen, were represented during the Silurian period in a simple genus, Hemicosmites, but they greatly increased in numbers in the seas of the Devonian period. They diminish in numbers, as we retire from that geological age; until those forms, which were so numerous and varied in the earliest seas, are now only represented by two genera.

The Old Red Sandstone rocks are composed of schists, sandstone, and limestones. The Hne of demarcation between the Silurian rocks and those which succeed them may be followed, in many places, by the eye; but, on a closer exami-r:T^!SB!!Wr!!if|!ff nation, the exact limits of the two systems become more difficult to fix. The beds of the one system pass into the other by a gradual passage, for Nature rarely admits of violent contrasts, and shows few sudden transitions. By-and-by, however, the change becomes very decided, and the contrast between the dark grey masses at the base and the superincumbent yellow and red rocks become sufficiently striking. In fact, the uppermost beds of the Silurian rocks are the passage-beds of the overlying system, consisting of flagstones, occasionally reddish, and called in some districts " tilestones." Over these lie the Old Red Sandstone conglomerate, the Caithness flags, and the great su- ;^Fig. 35. — Cupressocrinus crassus. perincumbent mass which forms the upper portion of the system. Though less abrupt than the eruptive and Silurian mountains, the Old Red Sandstone scenery is, nevertheless, distinguished by its imposing outline, assuming bold and lofty escarpments in the Vans of Brecon, in Grongar Hill, near Caermarthen, and in the Black Mountain of Monmouthshire, in the centre of a landscape which wood, rock, and river combine to render perfect. But it is in the north of Scotland where this rock assumes its grandest aspect, wrapping its mantle round the loftiest mountains, and rising oat of the sea in rugged and fantastic masses, as far north as the Orkneys. In Devon and Cornwall, where the rocks are of a calcareous, and sometimes schistose or slaty character, they are sufficiently extensive to have given a name to the series, which is recognised all over the world. In Herefordshire, Worcestershire, Shropshire, Gloucestershire, and South Wales, the Old Red Sandstone is largely developed, and sometimes attains the thickness of from 8,000 to 10,000 feet, divided