The Devonian system includes a complex series of deposits, which are of most interest in eastern Australia.
The Upper Devonian was a period of marine retreat; the crustal disturbances of the Lower Devonian were renewed and great quartz-pebble beaches were formed on the rising shore lines, producing the West Coast Range conglomerates of Tasmania, and the similar rocks to the south-east of Mansfield in Victoria.
The coal-seams must have been formed in wellwatered, lowland forests, at the foot of a high mountain range, built up by the Devonian earth movements.
The oldest rocks of Elba consist of schist and serpentine which in the eastern part of the island are overlaid by beds containing Silurian and Devonian fossils.
The Devonian dolomites, limestones and red sandstones cover immense tracts and appear on the surface over a much wider area.
And middle Russia they contain a special fauna, and it appears that the Lower Devonian series of W.
And central Russia, where only the Middle and Upper Devonian divisions are found.
The Falkland Islands consist entirely, so far as is known, of the older Palaeozoic rocks, Lower Devonian or Upper Silurian, slightly metamorphosed and a good deal crumpled and distorted, in the low grounds clay slate and soft sandstone, and on the ridges hardened sandstone passing into the conspicuous white quartzites.
In the extreme north-east are found the oldest rocks in the state - lower Devonian (the New Scotland beds of New York) and, not so old, an extension of the Lower Carboniferous which underlies the Warrior coalfields of Alabama, and which consists of cherts, limestones, sandstones and shales, with a depth of 800 to 900 ft.
The Devonian rocks of Canada (New Brunswick) have yielded several fossils which are undoubtedly wings of Hexapods.
We have undoubted fossil evidence that winged insects lived in the Devonian and became numerous in the Carboniferous period.
The basin of this river is formed mostly in Devonian shale, and is bounded on the W.
The rocks do not appear to differ very markedly from those farther south, but the Devonian is believed to be represented.
Brixham Cave, called also Windmill Hill Cavern, is a wellknown ossiferous cave situated near Brixham, on the brow of a hill composed of Devonian limestone.
Mogilev is built up of Devonian deposits in the north, of Cretaceous in the east, and of Tertiary elsewhere, but generally is covered with a thick layer of Glacial and later alluvial deposits.
Devonian rocks are believed to occur in Igaliko and Tunnudiorbik Fjords, in S.W.
A few Devonian forms have also been recorded from the Parry Archipelago, and Nathorst has shown the existence of Old Red Sandstone facies of Devonian in Traill Island, Geographical Society Island, Ymer Island and Gauss Peninsula.
Ephemeridae belong to a very ancient type of insects, and fossil imprints of allied forms occur even in the Devonian and Carboniferous formations.
Although rocks wholly or in large part vitreous are known from very ancient geological systems, such as the Devonian, they are certainly most frequent in recent volcanic countries.
Brachiopods first appear in the Lower Cambrian, and reached their highest development in the Silurian, from which upwards of 2000 species are known, and were nearly as numerous in the Devonian period; at present they are represented by some 140 recent species.
From the Devonian onwards the beds lie flat or dip at low angles.
Devonian beds cover a much more extensive area.
These bands are often concealed by more recent deposits, but it is clear that in this region the Devonian beds form a basin or synclinal with the Amazon for its axis.
Devonian beds also lie upon the older rocks in the Matto Grosso and other provinces in the interior of Brazil, where they generally form plateaux of nearly horizontal strata.
They belong to either the lower or the middle division of the Devonian system.
In the basin of the Lower Amazon the Carboniferous beds lie within the Devonian synclinal and crop out on both sides of the river next to the Devonian bands.
From the above account it will appear that, excepting near the coast and in the basin of the Amazon, there is no evidence that any part of Brazil has been under the sea since the close of the Devonian period.
Eruptive rocks occur in the Devonian and Carboniferous beds, but there is no evidence of volcanic activity since the Palaeozoic epoch.
Between Bingen and Bonn the Rhine forces its way through a hilly and rocky district belonging to the Devonian formation.
The slates are interbedded with limestones containing fossil brachiopods, which have led to their determination as Silurian or Devonian; but L.
The Silurian formation which covers Esthonia, appears in the northern part of Livonia, the remainder of the province consisting of Devonian strata.
In the Lahn district of Nassau (Germany) there are phosphate beds in Devonian rocks.
Those popularly known as " bluestones " belong to the Hamilton period of the Devonian formation and occur mainly between the Hudson and Delaware rivers.
The Devonian system is well exposed in the Reef ton mining field.
The western portion of Kotelnyi is built up of Middle Devonian limestones and slates, folded the same way, of which the fossil fauna is similar to that of the Urals.
Diabases pierce to Devonian rocks, and olivine rocks appear as dykes amidst the Triassic deposits.
The greater part of the Ardennes is occupied by a large area of Devonian beds, through which rise the Cambrian masses of Rocroi and Stavelot, and a few others of smaller size.
Upon the folded slates and schists which constitute these inliers the Devonian rests with marked unconformity; but north of the ridge of Condroz Ordovician and Silurian beds make their appearance.
The southern boundary of this belt is formed by a great thrust-plane, the faille du midi, along which the Devonian beds of the south have been thrust over the carboniferous beds of the coalfield.
Aspera, Spirifer verneuili, &c., and these the latter geologist assigns to the Devonian epoch.
At Cushendun, however, a coarse conglomerate is believed to be Devonian, while Lower Carboniferous Sandstones, with several coal-seams, form a small productive basin at Ballycastle.
There is an older series, ranging from the Devonian to the Cretaceous, which is folded and faulted and forms all the higher hills, and there is a newer series of Tertiary age, which lies nearly horizontal and rests unconformably upon the older beds.
The Devonian is visible only in Minorca, the Trias being the oldest system represented in the other islands.
The brachiopods, generally classed collectively as Spirifer mucronatus, follow at least five distinct lines of evolution in the Middle Devonian of North America, while more than twenty divergent lines have been observed by Grabau among the species of the gastropod genus Fusus in Tertiary and recent times.
Silurian and Devonian fossils have been reported at one or two localities, but for the present the observations are open to doubt.
Devonian System.The Devonian system appears in some parts of New England, throughout most of the Appalachian region, over much of the eastern interior from New York to the Missouri River, in Oklahoma, and perhaps in Texas.
Devonian I Ulsterian.
Devonian New Scotland beds.
The faunas of the early Devonian seem to have entered what is now the interior of the United States from the mid-Atlantic coast.
The Onondaga fauna which succeeded appears to have resulted from the commingling of the resident lower Devonian fauna with new emigrants from Europe by way of the Arctic regions.
The late Devonian fauna of the interior represents the commingling of the Hamilton fauna of the eastern interior with new emigrants from the north-west, a union which was not effected until toward the close of the period.
Like the earlier Palaeozoic systems, the Devonian attains its greatest known thickness in the Appalachian Mountains, where sediments from the lands of pre-Cambrian rock to the east accumulated in quantity.
Here clastic rocks predominate, while limestone is more abundant in the interior, If the maximum thicknesses of all Devonian formations be added together, the total for the system is as much as 15,000 ft.; but such a thickness is not found in any one pluce.
The Devonian system yields much oil and gas in western Pennsylvania, south-western New York, West Virginia and Ontario; and some of the Devonian beds in Tennessee yield phosphates of commercial value.
The Devonian system is not set off from theMississippian by any marked break.
This older classification, which has little support except that which is traditional, is still adhered to by many geologists; hut the fact seems to be that the system is set off from the Pennsylvanian (Upper Carboniferous) more sharply than the Cambrian is from the Ordoviciao, the Silurian from the Devonian, or the Devonian from the Mississippian.
Teau In the interior the Kinderhook series has a distribution similar to that of the Devonian; the Osage series is more widespread, pointing to progressive submergence; and the St Louis is still more extensive.
Uefore its close the sea of the Great Basin which had persisted since the Devonian was connected with the shallow sea which covered much of the interior of the United States.
The whole region is underlain by nearly horizontal and undisturbed rocks of the Palaeozoic from the Devonian downward.
This interior plain of the continent represents the area of the ancient sea by which it was occupied in Mesozoic times, with a more ancient margin towards the north-west against the Archean, where undisturbed limestones and other rocks of the Silurian and Devonian rest upon the downward slope of the Laurentian Shield.
Solenopsis; Devonian to Trias.
Cucullaea; recent and fossil from the Jurassic. All the other genera are fossil: Parallelodon; Devonian to Tertiary.