How to use Devonian in a sentence
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.Advertisement
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 rocks do not appear to differ very markedly from those farther south, but the Devonian is believed to be represented.Advertisement
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.Advertisement
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.Advertisement
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.Advertisement
The geological formation is Devonian.
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.
Here the rocks are all essentially horizontal and of Palaeozoic age, mainly Devonian.
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.
Near Dinant carboniferous beds are infolded among the Devonian.
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.
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.
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.
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.
Amphibia appeared before its close, and plant life was abundant and varied, though the types were not greatly in advance of those of the Devonian.
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.
In 1849 he became curator of the Natural History Museum at Wiesbaden, and began to study the Tertiary strata of the Mayence Basin, and also the Devonian fossils of the Rhenish provinces, on which he published elaborate memoirs.
On the Pocono plateau is a large deposit of a finegrained dark-blue stone of the Devonian formation which is known as the Wyoming Valley stone, and, like the New York " bluestone," which it closely resembles, is much used for window and door trimmings, steps and flagging.
The age of a great part of the Palaeozoic belts is somewhat uncertain, but Permian, Carboniferous, Devonian and Silurian fossils have been found in various parts of the chain, and it is not unlikely that even the Cambrian may be represented.
In many parts of the world there is no sharp line of demarcation between the Devonian and the Carboniferous rocks; neither can the fossil faunas and floras be clearly separated at any well-defined line; this is true in Britain, Belgium, Russia, Westphalia and parts of North America.
The Arthrodirans, so prominent during the Devonian period, disappeared before the close of the Carboniferous.
The fossil plants which are found in the upper beds of the preceding Devonian system are so closely related to those in the Lower Carboniferous, that from a palaeobotanical standpoint the two form one indivisible period.
In western Europe the advent of the Carboniferous period was accompanied by the production of a series of synclines which permitted the formation of organic limestones, free from the sediments which generally characterized the concluding phases of the preceding Devonian deposition.
The southern and larger part of the Rhine province, belonging geologically to the Devonian formations of the lower Rhine, is hilly.
In the Ardennes the rocks which constitute the ancient mountain chain belong chiefly to the Devonian System, but Cambrian beds rise through the Devonian strata, forming the masses of Rocroi, Stavelot, &c., which appear to have been islands in the Devonian sea.
The Ordovician and Silurian are absent here, and the Devonian rests unconformably upon the Cambrian; but along the northern margin of the Palaeozoic area, Ordovician and Silurian rocks appear, and beds of similar age are also exposed farther north where the rivers have cut through the overlying Tertiary deposits.
Near Dinant they are folded amongst the Devonian beds, but the most important band runs along the northern border of the Ardennes.
The Devonian sandstones contain malachite ores near Kielce, and copper has been worked there since the 15th century, though the mines are now neglected.
Along the northern border of the folded belt lies the coal basin of the Ruhr in Westphalia, which is the continuation of the Belgian coal-field, and bears much the same relation to the Rhenish Devonian area that the coal basin of Liege bears to the Ardennes.
Carboniferous and Devonian beds are also found south-east of the Bohemian massif, where lies the extensive coal-field of Silesia.
He also described the fossil plants of the Silurian, Devonian and Carboniferous rocks of Canada for the Geological Survey of that country (1871-1873).
It was doubtless this expectation that has led to the description of a number of Silurian and Devonian remains as algae upon what is now regarded as inadequate evidence.
It is believed, however, that the Devonian fossil, Nematophycus, is a Laminarian alga, but it is not until the late Secondary and the Tertiary formations that fossil remains of algae become frequent.
Some of the older rocks of the mountain regions have been referred to the Devonian, but the evidence cannot be considered conclusive.
Devonian and Carboniferous fossils have been found in several places in the Anti-Taurus.
Devonian fossils have been found near the Bosporus and Carboniferous fossils at Balia Maden in Mysia.
The shores of the Bosporus are composed in the northern portion of different volcanic rocks, such as dolerite, granite and trachyte; but along the remaining course of the channel the prevailing formations are Devonian, consisting of sandstones, marls, quartzose conglomerates, and calcareous deposits of various kinds.
Cambrian, Silurian, Devonian and Carboniferous deposits are found on the coasts of the Gulf of Finland and Lake Ladoga, and also along the coasts of the Arctic Ocean (probably Devonian), and in the Kjolen.
Supposed Silurian beds have been described at Portalegre, and in the same neighbourhood Devonian fossils have been found.
The primary rocks which appear at Mitushev Kamen are overlaid with thick beds of quartzites and clayslates containing sulphide of iron, with subordinate layers of talc or mica slate, and thinner beds of fossiliferous limestone, Silurian or Devonian.
The Palaeozoic beds have yielded fossils of Cambrian, Ordovician, Devonian and Carboniferous age.
In southern Bolivia Cambrian and Ordovician beds form the greater part of the eastern Andes, but farther north the, Devonian and Carboniferous are extensively developed, especially in the northeastern ranges.
The free library and art gallery of the corporation, a fourstoreyed building in Italian style erected in 1887, contains the library of the Rev. Rowland Williams (one of the authors of Essays and Reviews), the rich Welsh collection of the Rev. Robert Jones of Rotherhithe, a small Devonian section (presented by the Swansea Devonian Society), and about 8000 volumes and 2500 prints and engravings, intended to be mutually illustrative, given by the Swansea portrait-painter and art critic, John Deffett Francis, from 1876 to 1881, to receive whose first gift the library was established in 1876.
That bacteria have existed from very early periods is clear from their presence in fossils; and although we cannot accept all the conclusions drawn from the imperfect records of the rocks, and may dismiss as absurd the statements that geologically immured forms have been found still living, the researches of Renault and van Tieghem have shown pretty clearly that large numbers of bacteria existed in Carboniferous and Devonian times, and probably earlier.
The Russian Altai is composed mainly of mica and chlorite schists and slates, together with beds of limestone, and in the higher horizons Devonian and Carboniferous fossils occur in many places.
The weak areas in the crust caused by the earth movements were invaded by great masses of Devonian granites.
The rocks of the Devonian system rest unconformably upon the Silurian; but some beds of which the age is still uncertain are called Devono-Silurian.
The Devonian beds are well developed in the Blue Mountains, where the lower Devonian sediments at Mount Lambie are estimated to be Io,000 ft.
The Devonian rocks at Yalwal are sharply folded and are associated with a series of rhyolites and basic lavas.
The lower part of this series is probably Lower Devonian; and it is covered by shales and volcanic rocks belonging to the Upper Devonian.
In the extreme south-east of New South Wales, at the head of the Genoa river, are sandstones with Archaeopteris howitti, which are an extension of the Lower Devonian beds of Victoria; while farther to the east, at Eden and Twofold Bay, are Upper Devonian sandstones.
The Devonian system is separated from the Carboniferous by an interval, during which there were powerful earth movements; they produced a lofty mountain chain, running north and south across New South Wales.
Granites and granodiorites were intruded at this period into the older rocks, and altered the adjacent Devonian beds into slates and quartzites, and formed gold-quartz veins, which have been worked in the Devonian rocks at Yalwal.
The gold-quartz veins are mainly in the Ordovician and Silurian rocks; but some also occur in the Devonian, and there are impregnations of gold in tufas of Devonian age.
In Palaeozoic formations, from the Upper Devonian onwards, numbers of shrimp-like forms are found which have been referred to the Schizopoda and the Decapoda, but here again the scanty information which may be gleaned as to the structure of the limbs rarely permits of definite conclusions as to their affinities.
The peninsula of Cornwall and Devon may be looked upon as formed from a synclinal trough of Devonian rocks, which appear as plateaus on the north and south, while the centre is occupied by Lower Carboniferous strata at a lower level.
The Devonian strata on the south do not form such lofty elevations as those on the north, and are in consequence, like the plain of Hereford, very fertile and peculiarly adapted for fruit-growing and cider-making.
The Tamar flows from north to south on the Devonian plain, which lies between Dartmoor on the east and the similar granitic boss of Bodmin Moor (where Brown Willy rises to 1345 ft.) on the west.
The great variety of the rocks which meet the sea along the south of Cornwall and Devon has led to the formation of a singularly picturesque coast - the headlands being carved from the hardest igneous rocks, the bays cut back in the softer Devonian strata, The fjord-like inlets of Falmouth, Plymouth and Dartmouth are splendid natural harbours, which would have developed great commercial ports but for their remoteness from the centres of commerce and manufactures.
As for the boundaries of these ancient seas, we can say nothing with certainty, but it is of interest to note the evidence we possess of still older land conditions, such as we have in the old rocks of Shropshire, &c. In the Devonian period it is clear that an elevatory movement had set in towards the north, which gave rise to the formation of inland lakes and narrow estuaries in which the Old Red Sandstone rocks were formed, while in the south of England lay the sea with a vigorous coral fauna.
It was about this time that the Pennine Hills, the Lake District mountain mass, and the Mendip Hills were being most vigorously uplifted, while the granite masses of Cornwall and Devon wore perhaps being injected into the Carboniferous and Devonian rocks.
The volcanic outbursts which followed became feebler in the Devonian and Carboniferous periods and ceased with the Permian.
They appear to indicate a Devonian age.
Geologically, Banka resembles the Malay Peninsula, its formations being mainly granite, Silurian and Devonian slate, frequently covered with sandstone, laterite (red ironstone clay) of small fertility, and alluvium.
Regarding now the outcrops of bed-rock, there are exposures of Algonkian (doubtful, and at most a mere patch on Pilot Knob), Archean, Cambrian, Ordovician, Silurian, Devonian, sub-Carboniferous and Carboniferous.
Parallel to this in the latter locality, and lying also along the Mississippi near by to the north, as well as in the intervening country between the two rivers, are strips of Devonian.
Many of the species are common to the Devonian rocks of the Falkland Islands, North and South America and Europe, with perhaps a closer resemblance to the Devonian fauna of South America than to that of any other country.
The order was more abundantly represented in Palaeozoic times by the Heliolitidae from the Upper and Lower Silurian and the Devonian, and by the Thecidae from the Wenlock limestone.
It is about a mile east of Torquay harbour and is of a sinuous nature, running deeply into a hill of Devonian limestone.
The Silurian, Devonian and Carboniferous systems are represented - the Silurian and Devonian forming the greater part of the hills S.E.
A few patches of Upper Carboniferous are found on the borders of the hills near Ilfeld, Ballenstedt, &c., lying unconformably upon the Devonian.
It is only in the outer foldings of the highlands that Palaeozoic fossiliferous deposits are found - Silurian, Devonian, Carboniferous and Permo-Carboniferous.
This similarity is closest in Archaeocalamites, an ancient type found in Upper Devonian rocks; in this the strobilus consists of peltate sporangiophores inserted in whorls on the axis.
The granite invades this " greenrock " series at Slieve Gallion and elsewhere, but is itself pre Devonian.
Here the Ludlow strata are followed by a thick series of barren beds (the Dingle Beds), which have been variously claimed as Upper Silurian and Lower Devonian.
On the land-surface thus formed the Devonian lakes gathered, while the rivers poured into them enormous deposits of sand and conglomerate.
The numerous " felstone " dikes, often lamprophyric, occurring in the north and west of Ireland, are probably also of Devonian age.
Here there may be a local break between Lower and Upper Devonian strata.
The Yellow Sandstone contains Archanodon, the oldest known fresh-water mollusc, and plant-remains; the Coomhola Grits are marine, and are sometimes regarded as Carboniferous, sometimes as uppermost Devonian.
Archaean granite is thus exposed at Yampol and other places in Russia, and this is followed towards the west by Silurian and Devonian beds in regular succession - the Devonian being of the Old Red Sandstone type characteristic of the British Isles and of Northern Russia.
After Devonian times the region seems to have been dry land until the commencement of the Upper Cretaceous period, when it was overspread by the Cenomanian sea, and the deposits of that sea lie flat upon the older sediments.
Some unfossiliferous conglomerates, sandstones and dolomites in South Africa and on the west coast are considered to belong to the Cambrian, Ordovician and Silurian formations, but merely from their occurrence beneath strata yielding Devonian fossils.
The Devonian and Carboniferous formations are well represented in the north and south and in northern Angola.
Aurivillius considered that Pollicipes signatus showed a closer approach to the Balanidae than any other of the Lepadidae, but he, too, in ignorance of the Devonian Protobalanus (Whitf.), discoursed needlessly about the gap in the distribution.
The Devonian system is best represented by the massive conglomerates and quartzites, which form the West Coast Range extending from Mount Lyell on Macquarie Harbour, through Mounts Jukes, Owen, Lyell, Murchison and Geikie, to Mount Black.
The Devonian period, as in Victoria, was marked by a series of granitic intrusions, which altered the older beds on the contact, while the quartz-porphyry dikes, which are intrusive in the Silurian rocks at the Mount Bischoff tin mine, doubtless belong to this period.
The first species of the genus, Nematophycus Logani, was discovered by Dawson in 1856 in the Lower and Middle Devonian of Canada, and was described by him as a Conifer under the name of Prototaxites.
Ortoni (Penhallow), from the Devonian of Canada, the tubes are quite uniform, and there are no spaces or concentric rings.
Pachytheca, a spherical organism, usually about the size of a small pea, found in rocks of Silurian and Devonian age, has been much investigated and discussed, without any decisive light having been thrown on its nature.
They extend back through the Devonian, possibly to the Silurian system, but the systematic summary now to be given is based primarily on the rich materials afforded by the Carboniferous and Permian formations, from which our detailed knowledge of Palaeozoic plants has been chiefly derived.
In the oldest known Calamarian, however, Archaeocalamites (Devonian and Lower Carboniferous), the leaves were repeatedly forked.
Professor Nathorst has described a remarkable Devonian plant, Pseudobornia ursina (from Bear Island, in the Arctic Ocean), which shows affinity both with the Equisetales and Sphenophyllales.
The genus Bothrodendron, going back to the Upper Devonian, differs from Lepidodendron in its minute leaf-scars and the absence of leafcushions, the scars being flush with the smooth surface of the stem.
Under this name are included the fossil Lycopods of herbaceous habit, which occur occasionally, from the Devonian onwards.
The magnificent Devonian Fern Archaeopteris hibernica, with a somewhat Adiantiform habit, bore special fertile pinnae; the fructification is still imperfectly understood, but the presence of stipules, observed by Kidston, has been adduced in support of Marattiaceous affinities.
The genus Asterochlaena of Corda with a deeplylobed stele, goes back to the Devonian.
The family Calamopityeae, allied anatomically to Lyginodendreae, is of Devonian and Lower Carboniferous age.
Gymnospermous remains are common in Palaeozoic strata from the Devonian onwards.
The class Cordaitales extends back to the Devonian, and it must be borne in mind that our knowledge of their fructifications is practically limited to representatives from the latest Palaeozoic horizons.
The high development of the terrestrial flora in Devonian times renders it probable that land-plants existed far back in the Silurian ages, or still earlier.
Even in the Lower Devonian, Ferns and Lepidodendreae have been recognized; the Middle and Upper Devonian beds contain a flora in which all the chief groups of Carboniferous plants are already represented.
Considering the comparative meagreness of the Devonian record, we can scarcely doubt that the vegetation of that period, if adequately known, would prove to have been practically as rich as that of the succeeding age.
Among Devonian plants, Equisetales, including not only Archaeocalamites, but forms referred to Asterophyllites and Annularia, occur; Sphenophyllum is known from Devonian strata in North America and Bear Island, and Pseudobornia from the latter; Lycopods are represented by Bothrodendron and Lepidodendron; a typical Lepidostrobus, with structure preserved, has lately been found in the Upper Devonian of Kentucky.
In the Lower Carboniferous (Culm of Continental authors) many Devonian types survive - e.g.
From strata in New South Wales overlying Devonian and Lower Carboniferous rocks certain plants were discovered in the early part of the 19th century which were compared with European Jurassic genera, and for several years it was believed that these plant-beds belonged to the Mesozoic period.
The extraordinary abundance of Glossopteris in PermoCarboniferous rocks of Australia, and in strata of the same age in India and South Africa, gave rise to the term " Glossopteris flora for the assemblage of plants obtained from southern hemisphere rocks overlying beds containing Devonian and Lower Carboniferous fossils.
There is some evidence for the occurrence of similar Chara " fruits" in middle Triassic rocks; some doubtful fossils from the much older Devonian rocks have also been quoted as possible examples of the Charophyta.
Extinct, ranging from the Upper Devonian to the Trias.
Fish in general boomed during the Devonian, rapidly diversifying to fill newly-available niches.
In the Middle Devonian deeper water conditions have produced mudstones, thin limestones and slates which rarely yield fossils.
Actually rock crystals, they occur in the tension gashes that can be seen in the Devonian sandstone cliffs at various localities.
The Black Mountains are composed of nearly horizontal Devonian Lower Old Red Sandstone.
The Hereford fabrics would have needed tempering since the gravel found in them is not found naturally mixed with Devonian marl.
A possible basal unconformity has been observed with a fine grained conglomerate lying on the hard Devonian quartzite.
As one climbs up through Devonian sandstone along a wooded valley one can hear but not see a stream.
The package becomes sandy through the Late Devonian Ordovician.
The Lower Devonian beds are in the main terrestrial, or coarse littoral deposits, and volcanic rocks.
The Middle Devonian was marked by the same great transgression as in Europe and America; it produced inland seas, extending into Victoria, New South Wales and Queensland, in which were deposited limestones with a rich coral fauna.
Intrusions of granitic massifs in the Devonian period formed the primitive mountain axis of Victoria, which extends east and west across the state and forms the nucleus of the Victorian highlands.