Sedimentary sentence example
The sedimentary deposits include slate, limestone and sandstone.
The sedimentary rocks are affected by many dikes and sheets of igneous rock, some of the latter being extrusive and some intrusive.
In sedimentary rocks it occurs as detrital material.
In a large part of this basin the covering of sedimentary deposits is comparatively thin.
The most widely spread of the sedimentary beds belong to the Miocene period.'Advertisement
They are typical products of "regional" metamorphism, and are in nearly all cases older than the fossiliferous sedimentary rocks.
Deposits of brown iron ore of great economic value occur in many sedimentary rocks, such as the Lias, Oolites and Lower Greensand of various parts of England.
Others are probably sedimentary rocks, especially those which contain much muscovite.
A few geologists regard the sedimentary rocks here classed as Keweenawan as Palaeozoic; but they have yielded no fossils, and are unconformable beneath the Upper Cambrian, which is the oldest sedimentary formation of the region which bears fossils.
In that belt they consist mostly of greywacke, grit, shale and other sedimentary rocks, but in the southwest of Ayrshire they include some thick lenticular bands of limestone.Advertisement
They occur (a) in crystalline igneous and metamorphic rocks as an original constituent, (b) in veins associated with igneous rocks, and (c) in sedimentary rocks either as organic fragments or in secondary concretionary forms.
Schists in the common acceptance of that term are really highly crystalline rocks; fissile slates, shales or sandstones, in which the original sedimentary structures are little modified by recrystallization, are not included in this group by English petrologists, though the French schistes and the German Schiefer are used to designate also rocks of these types.
Where a thick group of coarse hard grits intercalated in the sedimentary rocks crops out it rises into a chain of lofty rugged hills, of which Ben Ledi and Ben Vorlich are examples.
Transitions between schists and normal igneous or sedimentary rocks are often found.
Slate is a soft sedimentary rock, which easily splits into thin layers.Advertisement
It consists of a series of plateaus formed of sedimentary rocks which mainly belong to three formations of widely separated ages, and which rest on a platform of granitic and metamorphic rocks.
The rocks at the base of the slopes are granite, the upper escarpments are of sedimentary rocks.
Throughout the whole of Arabia, so far as is known, the sedimentary beds show no signs of any but the most gentle folding.
Unlike Australia, its geological structure is unusually varied, and owing to its instability, it includes, for its size, an unusually complete series of marine sedimentary rocks.
The sedimentary deposits of the Tertiary era do not occupy a very wide area.Advertisement
Locally both the sedimentary and igneous parts of the group have been highly metamorphosed; but as a rule the alteration of the sedimentary portions has not gone so far that stratigraphic methods are inapplicable to them, though in some places detailed study is necessary to make out their structure.
Iron ore occurs in the sedimentary part of the Huronian, especially in Minnesota, Michigan, Wisconsin and parts of Canada.
The copper of the Lake Superior region is in the Keweenawaii system, chiefly in its sedimentary and amygdaloidal parts.
They consist, in most parts of the country, of unconsolidated sediments, consisting of gravel, sand, clay, &c., together with large quantities of tuff, volcanic agglomerate, &c. Some of the sedimentary formations are of marine, some of brackish water, and some of terrestrial origin.
From the map it will be noticed that the largest and most thickly strewn lakes occur within five hundred or a thousand miles of Hudson Bay, and belong to the Archean protaxis or project beyond its edges into the Palaeozoic sedimentary rocks which lean against it.Advertisement
This latest and also highest range was formed by tremendous thrusts from the Pacific side, crumpling and folding the ancient sedimentary rocks, which run from the Cambrian to the Cretaceous, and faulting them along overturned folds.
He argued also in favour of the original horizontality of sedimentary deposits.
In some cases these sedimentary rocks lie deeply buried under lavas poured out by volcanoes long extinct.
This view of its origin is now known not to be applicable to the Archean as a whole, since this system contains some metamorphosed sedimentary rocks.
Metamorphosed sedimentary rocks are widely distributed in the schistose series, but they are distinctly subordinate to the meta-ignecius rocks, and they are so highly metamorphic that stratigraphic methods are not usually applicable to them.Advertisement
The Keewatin and Huronian, consisting of greenstones, schists and more or less metamorphosed sedimentary rocks, are of special interest for their ore deposits, which include most of the important metals, particularly iron, nickel, copper and silver.
The several ranges of the Cordillera show very different types of structure and were formed at different ages, the Selkirks with their core of pre-Cambrian granite, gneiss and schists coming first, then the Coast Ranges, which seem to have been elevated in Cretaceous times, formed mainly by a great upwelling of granite and diorite as batholiths along the margin of the continent and sedimentary rocks lying as remnants on their flanks; and finally the Rocky Mountains in the Laramie or early Eocene, after the close of the Cretaceous.
The Great Valley Region consists of folded sedimentary rocks, extensive erosion having removed the soft layers to form valleys, leaving the hard layers as ridges, both layers running in a N.E.-S.W.
In some places along the coast there is a narrow strip of decomposed coral limestone; often, too, a coral reef has served to catch the sediment washed down the mountain side until a deep sedimentary soil has been deposited.
Timor consists of a core of ancient rocks (Archean?) upon which rest Permian and later deposits of sedimentary origin.Advertisement
In the case of the Alps it seems natural enough that the crystalline masses of Bohemia, the Black Forest and the central plateau of France should be firmer than the more modern sedimentary deposits; but it is not so easy to understand why the Mesozoic rocks of southern Germany resisted the folding, while those of the Jura yielded.
It occurs crystallized, commonly in cubes, in schistose and slaty rocks, and less abundantly in the younger sedimentary deposits.
Blende, is also found sporadically in sedimentary rocks; for example, in nodules of clay-ironstone in the Coal Measures, in the cement-doggers of the Lias, and in the casts of fossil shells.
The mountain range that runs out towards the north-east of Sicily is composed of crystalline rocks precisely similar to those forming the parallel range of Aspromonte in Calabria, but both of these are girt about by sedimentary strata belonging in part to an early Tertiary epoch.
The core is formed by the mountain masses of Rhodope, Belasitza, Perin and Rila; and here Palaeozoic and Mesozoic beds are absent, and the earliest sedimentary deposits belong to the Tertiary period and lie flat upon the crystalline rocks.Advertisement
The lowest of these younger rocks are the various sedimentary and volcanic members of the Old Red Sandstone.
The central, southern and eastern Highlands are occupied by metamorphosed sedimentary and igneous rocks, to which has been provisionally assigned the name of Dalradian, from the old Celtic kingdom of Dalriada.
Immense -sheets of dolerite, gabbro, or allied basic rocks indicate eruptive materials intruded as sills or poured out as lavas contemporaneously with the sedimentary formations among which they lie.
The end of the Cretaceous period saw the beginning of a series of great earth movements ushered in by volcanic eruptions on a scale such as the earth has never since witnessed, which resulted in the upheaval of the Himalayas by a process of crushing and folding of the sedimentary rocks till marine fossils were forced to an altitude of 20,000 ft.
Sedimentary rocks of the same age form a belt to the north, and include Skiddaw (3054 ft.); while to the south a belt of Silurian rocks, thickly covered with boulder clay, forms the finely wooded valleys of Coniston and Windermere.Advertisement
The great majority of the islands bear evident marks of volcanic origin, and there are numerous volcanic cones on the north side of the chain, some of them active; many of the islands, however, are not wholly volcanic, but contain crystalline or sedimentary rocks, and also amber and beds of lignite.
Subsequent denudation has removed the sedimentary covering and exposed the igneous core.
Owing to its confinement between these high banks, and to the great amount of sedimentary matter which the river brings down with it, its bed has been gradually raised, so that in its lower course it is in many places above the level of the surrounding country.
Its high crystalline rocks, covered with sedimentary formations, descend abruptly towards the delta, but more gradually towards the south, where the Bulgarian steppes encroach upon Rumanian soil.
Superficially, each is a simple rolling plateau, much broken by erosion (though considerable undissected areas drained by underground channels remain), especially in the east, and dotted with hills; some of these are residual outliers of the eroded Mississippian limestones to the west, and others are the summits of an archaean topography above which sedimentary formations that now constitute the valley-floor about them were deposited and then eroded.Advertisement
The Central Cordillera is the direct continuation of the Eastern Cordillera of Ecuador, and is formed chiefly of gneiss and other crystalline rocks, but sedimentary deposits of Cretaceous age also occur.
Among the sedimentary rocks we have, for example, in the clay slates of the Silurian formations, rocks no less cracked and fissured than others, but generally quite impermeable by reason of the joints being packed with the very fine clay resulting from the rubbing of slate upon slate in the earth movements to which the cracks are due.
Sedimentary rocks, formed below the sea or salt lagoons, must originally have contained salt water in their interstices.
Where the streams cut their way through sheets of basaltic lava their banks are steep, almost vertical cliffs, but where they cut through sedimentary rocks the sides have a more gentle slope.
Slates, schists, quartzites and limestones form the greater part of the hills, but the Brocken and Victorshohe are masses of intrusive granite, and diabases and diabase tuffs are interstratified with the sedimentary deposits.
In the south and west the sedimentary rocks most largely developed are of ancient, pre-Carboniferous date, interrupted by considerable patches of granite, serpentine and other crystalline rocks.
It belongs to the later series of transverse upheavals, and consists almost entirely of sedimentary rocks.
In the midst of the sedimentary region are two well-recognized masses of plutonic rocks, belonging to the syenites, sometimes quartziferous in structure.
In the sedimentary region volcanic rocks are very numerous; the most extensive of these is a tract of country, more than 80 m.
On the flanks of the primitive western axis certain ancient sedimentary strata are thrown into folds which were completed before the commencement of the mesozoic period.
None of these earth movements affected the interior, for here the continental mesozoic deposits rest, undisturbed by folding, on the primary sedimentary and crystalline rocks.
The general occurrence of jasper-bearing rocks is of interest, as these are always present in the ancient pressure-altered sedimentary formations of America and Europe.
Preserved in the formation known as the Dwyka Conglomerate, are evidences that at this time the greater portion of South Africa was undergoing extreme glaciation, while the same conditions appear to have prevailed in India Table Of Formations Sedimentary.
No Archean rocks are exposed in Nebraska, and the sedimentary formations are undisturbed in situ.
The Alleghany Plateau is the north-westernmost division of the Appalachian system; it is an eroded mass of sedimentary rock sloping north-westward to the Prairie and Lake Plains and reaching south-west from the south-western part of New York state through Tennessee and into Alabama.
Geologically, Armenia consists of archaic rocks upon which, towards the north, are superimposed Palaeozoic, and towards the south later sedimentary rocks.
During recent times the most destructive were those of, 8 r 1, 1820, 1840 and 1893; and, although the prevailing geological formations are sedimentary, chiefly calcareous, there seems no doubt that these disturbances are of igneous origin.
Our aim is not simply to give a summary of the most striking botanical features of the several floras that have left traces in the sedimentary rocks, but rather to attempt to follow the different phases in the development of the vegetation of the world, as expressed in the contrasts exhibited by a comparison of the vegetation of the Coal period forests with that of the succeeding Mesozoic era up to the close of the Wealden period.
The MT survey confirmed the existence of a Mesozoic sedimentary basin between lava flows and the Precambrian basement.
He left BGS in 2000 to form HM Research Associates in order to continue provenance research in sedimentary basins around the world.
Volcanic rock of high calcium carbonate underlies the western region; sedimentary sandstone occurs on the coastal flank.
Below the cretaceous Tertiary escarpment, the low ground is underlain by soft sedimentary rocks of the Triassic Mercia Mudstone Group.
This project will involve detailled field studies of the sedimentary composition, palaeocurrent analysis, stratigraphic breaks, unconformities, and sedimentary facies.
The sedimentary schists or paraschists have three great subdivisions, the mica-schists and chlorite-schists (which correspond in a general way to shales or clay rocks) the calc-schists (impure limestones) and the quartz-schists (metamorphosed sandstones).
The bedrock of the district consists of some of the oldest sedimentary rock exposed in the British Isles.
In this huge region is where the sedimentary oil basins are to be found.
The uplifted sedimentary strata are very clearly visible in many of these pictures.
Be able to find your way through the modern literature jungle in the field of sedimentary geology.
A calcareous sedimentary deposit, with recent shells, altered by the contact of superincumbent lava, its horizontality and extent.
In the example of Figure 3, tho, the sedimentary P-wave velocities are significantly lower than the basalt S-wave velocities.
Established around the Wilamette River, which runs North to South through the heart of the region, the Wilamette Valley provides volcanic and sedimentary soils that impart distinctive flavors to the wine.
So far as is known, the Malay Peninsula consists of an axial zone of crystalline rocks, flanked on each side by an incomplete band of sedimentary deposits.
The prevailing formations appear to be granites which are veined with white quartz, and underlie old sedimentary brown sandstone and limestone formations.
These beds, as well as the Cretaceous series, from which they are as yet only imperfectly distinguished, are associated with sheets of basalt, which penetrate them in great dikes, and in some places, owing to the wearing away of the softer sedimentary rocks, stand out in long walls running across the beds.
They constitute, in fact, an incomplete rim around the basin of sedimentary beds which occupies the Amazonian depression.
Outside the lower end of each large transverse glen there is a scree of sedimentary matter.
On the whole, the Proterozoic rocks are predominantly sedimentary and subordinately igneous.
Determined by the inequalities of surface of the overlying mantle of sedimentary material, they would be wholly independent of the geological structure of the rocks lying.
The Eastern Cordillera is composed of gneiss, mica and chlorite schist and other crystalline rocks of ancient date; the Western Cordillera, on the other hand, is formed of porphyritic eruptive rocks of Mesozoic age, together with sedimentary deposits containing Cretaceous fossils.
In at least two places sedimentary rocks are found at considerable elevations.
Finally the basic dykes of dolerite, basalt and augite-andesite are abundant and traverse the various sedimentary formations and the granite.
The sedimentary deposits were formerly believed to be Palaeozoic, but Jurassic fossils have since been found in them, and it is probable that several different formations are represented.
But the Muller range, the Madi plateau, and the Schwaner Mountains of west Borneo, consist chiefly of almost undisturbed sedimentary and volcanic rocks of Tertiary age.
Besides the crystalline gneiss and halleflinta there are also sedimentary deposits which are believed to be of pre-Cambrian age.
The geological structure is remarkably uniform, the plateau consisting mainly of sedimentary deposits resting on crystalline rocks.
The second is the zone of the snowy peaks and of the lower Himalaya, and is composed chiefly of crystalline and metamorphic rocks together with unfossiliferous sedimentary beds supposed to be of Palaeozoic age.
The hills, known as the Chiquitos, which rise from the plains of eastern Bolivia, are composed of ancient sedimentary rocks of unknown age.
The bedrock of the district consists of some of the oldest sedimentary rock of the district consists of some of the oldest sedimentary rock exposed in the British Isles.
The seabed is predominantly sedimentary, ranging between mud and cobbles but consisting mainly of sand.
In many areas much early building utilized soft sedimentary rocks, which tend to be of relatively low magnetic susceptibility.
Since the specimens have become dry, it is rather more easy to distinguish the decomposed igneous rocks from the sedimentary tuffs.
The ore is chiefly haematite, and has been developeci from antecedent ferruginous sedimentary deposits, through concentration and purification by ground water.
The lower part of the Keweenawan system consists of a great succession of lava flows, of prodigious thickness.- This portion of the system is overlain by thick beds of sedimentary rock, mostly conglomerate and sandstone, derived from the igneous rocks beneath.
In general, however, the central area is one of faulting rather than of folding, and the sedimentary beds sometimes lie in troughs formed by faults.
To the east of the dislocation of the Great Glen these puzzling rocks may also be met with, though in that tract most of the surface comprises sedimentary and igneous rocks, the metamorphism of which has varied much.
In the paraschists, though fossils are exceedingly rare, sedimentary structures such as bedding and the alternation of laminae of fine and coarse deposit may frequently be preserved.
Such changes seem, however, to have been very rapidly accomplished, as pebbles of completely formed coal are commonly found in the sandstones and coarser sedimentary strata alternating with the coal seams in many coalfields.
The phosphatic rocks which occur among the sedimentary strata are the principal sources of phosphates for commerce and agriculture.
These terminal lakes, or more accurately sedimentary plains, are therefore almost always dry."
The oldest rocks consist of granite and schist, penetrated by intrusive dykes, and upon this foundation rest the flat-lying sedimentary deposits, beginning with a sandstone like the Nubian sandstone of Egypt.
Inasmuch, however, as the floor on which the overlapping strata rest is, like the rest of the Laurentian and Superior Oldland, a worn-down mountain region, and as the lowest member of the sedimentary series usually contains pebbles of the oldiand rocks, the better interpretation of the relation between the two is that the visible oldiand area of to-day is but a small part of the primeval continent, the remainder of which is still buried under the Palaeozoic cover; and that the visible oldiand, far from being the first part of the continent to rise from the primeval ocean, was the last part of the primeval continent to sink under the advancing Palaeozoic seas.
There are ancient rocks, however, in New Caledonia, which .has a geological affinity with New Zealand; old sedimentary rocks are known in New Pomerania, besides granite and porphyry, and slates, sandstone and chalk occur in Fiji, as well as young volcanic rocks.