Sediments Sentence Examples
The mountain structures originated in three great orogenic periods, the earliest in the Archean, the second at the end of the Palaeozoic and the third at the end of the Mesozoic. The Archean mountain chains, which enclosed the present region of Hudson Bay, were so ancient that they had already been worn down almost to a plain before the early Palaeozoic sediments were laid down.
The marine-part of the Lafayette is probably covered by sediments of later age.
As in other comparable cases, this figure does not make allowance for the oblique attitude in which the sediments were deposited, and should not be construed to mean the vertical thickness of the system.
The Mesozoic sediments were almost entirely laid down to the west and south-west of the protaxis, upon the fiat-lying Palaeozoic rocks, and in the prairie region they are still almost horizontal; but in the Cordillera they have been thrust up into the series of mountain chains characterizing the Pacific coast region.
The ridges and intervening valleys, long parts of which have an approximately parallel trend from south-west to north-east, were formed by the erosion of folded sediments of varying hardness, the weak belts of rock being etched out to form valleys and the hard belts remaining as mountain ridges.Advertisement
They contain a great variety of sediments and igneous rocks.
The climate of the period, at least in its earlier part, seems to have been arid like that of the Permian, as indicated both by the paucity of fossils and by the character of the sediments.
Alumina is high in the finer clays (18 to 30%), and they are the most aluminous of all sediments, except bauxite.
Land masses are denuded and minerals containing silicates are carried down to the sea as sediments.
Secondary products, such as glauconite, phosphatic concretions and manganese nodules, occur though less frequently than in the hemipelagic sediments.Advertisement
Both of these ranges of hills are composed of hard crystalline rocks, and between them lies the lowland eroded on the weaker sandstones and sediments.
Enormous quantities of borax, already exploited, and of nitrate of soda, are known to be present in the surrounding country, the former as almost pure borate of lime in Tertiary lake sediments.
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.
In India the same flora occurs in a thick series of fresh-water sediments, known as the Lower Gondwana system, including basal boulder-beds like those of Australia.
Afghanistan, forming part of a thick series of marine beds known as the Salt Range group. This group of sediments in the extrapeninsular area of India includes a basal boulder-bed, referred on convincing evidence to the same geological horizon as the glacial deposits of the Indian peninsula (Talchir boulder-beds), South.Advertisement
Moreover, the Triassic rocks of southern Europe and other regions are typical marine sediments.
In following the progress of plant-life through those periods in the history of the earth of which records are left in ancient sediments, seams of coal or old land-surfaces, we recognize at certain stages a want of continuity between the floras of successive ages.
The southernmost mountain system of the Anti-Atlas thus consists of crystalline basement and Paleozoic sediments.
Bone in packing and floor materials derived from natural sediments is often uncharred and exhibits pale birefringence and signs of weathering.
This is due in part to the highly calcareous nature of some of the mineral sediments at the site.Advertisement
Therefore, we are using the box corer, which allows us to recover undisturbed surface sediments from the seafloor.
We went downstairs and waded ankle deep in muddy water and sandy sediments.
Samples of pollen taken from cores bored from deep peat bogs or lake sediments are stratified, with the earliest part lying deepest.
Techniques using in situ produced cosmogenic nuclides have been developed to date sediments deposited over the past several million years Granger et al.
We have 5 days of allocated science onboard in which to collect cores of deep sea sediments - made up of beautiful fossil diatoms!Advertisement
It consists of Permian-Triassic sediments, capped by Jurassic dolerite, and generally occurs above about 600m, except in the east.
In this proposal a series of experiments with graded sediments are detailed which will take place in the tilting flume at HR Wallingford.
I have studied long-term fire history of boreal forests in Finland by using fine resolution pollen and charcoal analyzes of varied lake sediments.
The sediments mainly comprise richly fossiliferous sands deposited in shallow sub-tropical coastal seas about 45 million years ago.
The distribution of this element in stream sediments is controlled by the underlying bedrock geology.
This means that coarse sediments may be located in hollows with no drainage exit, leading to the formation of groundwater gleys or peat.
This lecture describes the action of wind upon desert sediments and the resultant desert landforms.
The rocks of this period are characteristically red in color due to the oxidation of iron-rich minerals in the sediments under the arid conditions.
These sediments have not been well pugged or mixed and include unworked aggregates.
Similar patterns of development sometimes exacerbate the consequences of collapse of the unconsolidated sediments forming sandbars.
These sediments were formed in an arid, enclosed shallow seaway or saline lake between 230 and 215 million years ago.
These finds are now under threat as they become exposed due to the eroding sediments.
At present, the dredged sediments are disposed of outside the harbor, thus losing valuable mud from its ecosystem.
These conclusions are based on analysis of the carbonate content of offshore, beach and estuarine sediments.
Sublittoral sediments are predominantly medium sands with a low organic content.
However, some reworking of seabed sediments in the Solent is a probable auxiliary source.
This indicates that deep-sea sediments constitute a very important source of DON to the world ocean.
Clare Britton has added carbonate sediments and weathering to the simple Earth system model to look even further into the future.
This research also includes studies of the migration of gas through sediments, and the effect of gas on marine slope stability.
The method optically stimulated luminescence (OSL) is a way of establishing the age of soil sediments.
As the low-lying plains are altogether an alluvial deposit, the coarser sediments accumulate in the regions where the river first overflows its banks to spread out over the plains.
The coarser particles of the sediments are deposited near the shore as gravels, sand and muds, but the very fine particles remain in suspension in the colloidal form, and some of this may be acted upon by marine bacteria or (it is surmised) even utilized by diatoms as a source of silica.
Exposed riverine sediments (ERS) represent important river margin habitats that are associated typically with highly dynamic rivers with unregulated flow regimes.
Typically found scuttling about in vegetation or in the surface layers of bottom sediments, occasionally in open water.
Challenger Division scientists have been studying the seafloor sediments in the Canary Basin for over 20 years.
Whatever the stimulus for erosion and deposition, the sediments within these hollows typically contain an important record of local environmental change.
The role of biological effects studies and the use of artificial substrata and sediments in marine pollution monitoring is also discussed.
Controls on the organic content and composition of surficial sediments from sites spanning the Arabian Sea oxygen minimum zone.
This is thought to be due to the high quantities of suspended sediments and yellow substances in the Baltic.
It outlines important methods for determining the types, composition, aerial extent, and thickness of sediments on the bottom of Sebago Lake.
Immediately fringing the tidal zone there may be sediments that have remained waterlogged since deposition and are classified as raw gley soils.
Seasonal inflow may, for example, winnow out sediments from breccias and other areas, to redeposit them elsewhere.
The carbon cycle is the process by which carbon travels between the atmosphere, land, the oceans and the sediments below ground (where fossil fuels are stored).
Lees are the naturally occurring sediments that form in the wine during fermentation.
Clostridia and their spores exist all over the world, especially in soil and aquatic sediments.
These filmy sediments, cloudiness, and globular strands floating in the cider make up the Mother, and this is where you'll derive most of the health benefits.
The northern part can best be regarded as a low plateau (once marine sediments) sloping southward, traversed by the large diluvial valleys of the Mississippi, Red and Ouachita rivers, and recut by smaller tributaries into smaller plateaus and rather uniform flat-topped hills.
They may safely be considered to be among the oldest auriferous sediments of the world.
A very thin soil covers the Edwards Plateau, but on the Llano Estacado are brownish and reddish loams derived from the sediments of a Neocene lake.
The Paleozoic sediments, ranging in age from Cambrian to Permian, occupy the Great Valley, the Valley Ridges and the plateaus still farther west.
Matthew, and are shown to contain fluviatile or channel beds with water and river-living forms, and neighbouring flood-plain sediments containing remains of plains-living forms. Thus we may complete the former physiographic picture of a vast flood plain east of the Rocky Mountains, traversed by slowly meandering streams.
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.
The site of these mountains had been, for the most part, an area of deposition throughout the Palaeozoic era, and the body of sediments which had gathered here at the western base of Appalachia, by the close of the Pennsylvanian period, was very great.
At this time these sediments, together with some of Appalachia itself, began to be folded up into the Appalachian Mountains.
Triassic SystemThis system has but limited representation in the eastern part of the United States, being known only east of the Appalachian Mountains in an area which was land throughout most of the Palaeozoic era, hut which was deformed when the eastern mountains were developed at the close of the Palaeozoic. In the troughs formed in its surface during this time of deformation, sediments of great thickness accumulated during the Triassic period.
These sediments are now mostly in the form of red sandstone and shale, with conglomerate, black shale and coal in some places.
This widespread submergence, followed by the deposition of marine sediments on the eroded surface of Comanchean and older rocks, is the physical reason for the separation of the system from the Comanchean.
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.
The sites of deposition varied as the period progressed, for the warping and faulting of the surface, the igneous extrusions, and the deposition of sediments obliterated old basins and brought new ones into existence.
Under these conditions sediments from the high lands were washed out and distributed widely over the plains, giving rise to a thin but widespread formation of ill-assorted sediment, without marine fossils, and, for the most part, without fossils of any kind, and resting unconformably on Cretaceous, Eocene and Miocene formations.
Clastic sediments are less abundant and there are fewer breaks in the succession.
Sediments approaching to the culm type, with similar flora and fauna, were deposited in synclinal hollows in parts of France and Spain.
Looking eastward, towards central and northern Russia, we find a wider and much more open sea; but the continental type of deposit prevailed in the northern portion, and here, as in Scotland, we find coal-beds amongst the sediments (Moscow basin).
Similar events were meanwhile happening in North America, for the seas were steadily filled with sediments which drove them from the northeast towards the south-west, and doubtless those movements which at the close of this period uplifted the Appalachian mountains were already operative in the same direction.
When the land reappeared a new series of valleys would at once begin to be eroded; and the subsequent degradation of these overlying sediments might reveal portions of the older topography, as in the case of the Great Glen, Lauderdale, and other ancient valleys.
The plains sediments contain important coal beds, which are worked in nearly every county in the state.
The highland rocks no doubt once extended along the whole length of the state from north to south; but they are now crossed by a band of Upper Palaeozoic sediments, which extend up to the valley of the Hunter river and separate the Blue Mountains and the Southern Highlands of New South Wales from the New England tableland to the north.
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 terraces represent the out-cropping edges of hard sandstone layers included in the series of plateau sediments, and are named according to the colour of the rock exposed in the south-facing escarpments, the Pink Cliffs (highest), White Cliffs and Vermilion Cliffs.
Most interesting among these are the Henry Mountains, formed by the intrusion of molten igneous rock between the layers of sediments, causing the overlying layers to arch up into dome mountains.
The Jurassic and Cretaceous beds are ordinary marine sediments, but from the Cenomanian to the Oligocene the deposits are of the peculiar facies known in the Alps and Carpathians as Flysch.
These sediments are fine and tenacious; their principal components, in addition to clay, being small grains of quartz, zircon, tourmaline, hornblende, felspar and iron compounds.
It is interesting to observe, as will be shown later, that during the Mesozoic era there was a land-mass in the north of Asia and another in the south, and between them lay the sea in which ordinary marine sediments were deposited.
Recent limestones are being produced in this way and also in some places by the precipitation of calcium carbonate by sodium or ammonium carbonate which has been carried into the sea or formed by organisms. The precipitated carbonate may agglomerate on mineral or organic grains which serve as nuclei, or it may form a sheet of hard deposit on the bottom as occurs in the Red Sea, off Florida, and round many coral islands in the Pacific. Only the sand and the finest-grained sediments of the shore zone are carried outwards over the continental shelf by the tides or by the reaction-currents along the bottom set up by on-shore winds.
The question is of the age of the sediments from which these were taken.
While igneous and metamorphic crystalline rocks form the bulk of the Adirondack area, it is surrounded by a ring of ancient Palaeozoic sediments in which these peripheral lowlands have been developed.
From these high lands sediments were borne down to lodge on the low lands adjacent.
Thus the lower Eocene has some lignite in the eastern Gulf region, while in Teias lignite and saliferous and gypsiferous sediments are found, though most of the system is marine and of shallow water origin.
Later the sediments lying to the south-east of this " protaxis," or nucleus of the continent, were pushed against its edge and raised into the Appalachian chain of mountains, which, however, extends only a short distance into Canada.
The great variety of conditions under which the sediments and limestones were formed naturally produced corresponding inequalities in the thickness.
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.
In North America, the crustal movements at the beginning of the period are less evident than in Europe, but a marked parallelism exists; for in the east, in the Appalachian tract, we find detrital sediments prevailing, while the open sea, with great deposits of limestone, lay out towards the west in the direction of that similar open sea which lay towards the east of Europe and extended through Asia.
The Cambrian rocks in this region are nearly all soft sediments, some 600 ft.