According to this view stratified rocks could have been formed very early in the history of the earth, and in this connection it is interesting to note that the oldest known rocks are actually of sedimentary origin.
A sedimentary rock consisting essentially of carbonate of lime which generally represents accumulation of shells of organisms, but in some cases precipitates from solution.
Hematite is extremely widespread in rocks of all ages, especially in metamorphic and sedimentary rocks.
Sedimentary beds as deposited lie flat or nearly flat, but subsequently they have often been deformed by folding and faulting.
A break in the regular succession of sedimentary rocks, indicated by the fact that one bed rests on the eroded surface of one or more beds which may have a distinctly different dip from the bed above.
It would be most evident that the mountains consist of strata, that is sedimentary rocks, such as sandstone, shale and limestone, which were deposited under water.
Any igneous or sedimentary rock which has undergone metamorphism, that is notable alteration from its original condition.
A sedimentaryrock consisting of consolidated or cemented gravel.
It is a metamorphic rock derived from either sedimentary or igneous rock, more commonly the former.
Grenville), they very clearly were forced or intruded, while molten, into the sedimentary rocks, thus proving these latter to be the older.
They constitute a complex lot of crystalline metamorphic rocks, combining certain characteristics which lie below the base of the determined sedimentary succession.
A characteristic feature of sedimentary deposits is a layered structure known as bedding or stratification.
The geologists sought to estimate the period of time that must have been required for the deposit of the sedimentary rocks now observed to make up the outer crust of the earth.
The diversified sedimentary series is folded and faulted on a large scale with broad structural undulations visible for miles along the abrupt valley walls.
The sedimentary beds in the background of the first diagram are hypothetical and are supposed to correspond to the quartzites of the Majes Valley at Aplao.
The Silurian is from a Bolivian locality south of La Paz but in the great belt of shales, slates, and schists which forms one of the oldest sedimentary series in the Eastern Andes of Peru as well as Bolivia.
On the western flanks of the granite range no corresponding sedimentary deposits are found in this latitude.
The invasion of the granite was accompanied by moderate absorption of the displaced rock, and more especially by the marginal pushing aside of the sedimentary rim.
At any rate we have here no Devonian sediments, a characteristic shared by almost all the great sedimentary formations of Peru.
Space was made for them by displacing the sedimentary cover and by a marked shortening of the sedimentary rim through such structures as overthrust faults and folds.
The longest, and, from the human standpoint, the most important, break in the sedimentary record is that of the present wherever degradation is the predominant physiographic process.
Outside the lower end of each large transverse glen there is a scree of sedimentary matter.
These terminal lakes, or more accurately sedimentary plains, are therefore almost always dry.
Besides these sedimentary rock there are formations like granite, showing the influence of heat.
The same may be said of the Pancake Range and other mountain chains of igneous rock in Nevada, while the adjacent ranges composed of sedimentary rocks are rich in ore deposits of various kinds.
On the contrary, the masses of unfused and always relatively cool sedimentary rocks which form the most highly metalliferous mountain ranges (White Pine, Toyabe, etc.
These are zones or layers of a sedimentary rock, to the bedding of which they are conformable, impregnated with ore derived from a foreign source, and formed long subsequent to the deposition of the containing formation.
It is mathematically certain that, in any given vertical linear section of an undisturbed series of sedimentary deposits, the bed which lies lowest is the oldest.
The hills in the vicinity and at the base of the Tower are composed of red, yellow, green, or gray sedimentary rocks that consist of sandstone, shale, or gypsum.
From one-half to about a mile from the Tower the sedimentary rocks dip gently from 2° to 5° away from the Tower to form a broad dome.
Locally, landslides of this talus have extended through valleys in the sedimentary rock down almost to the level of the surrounding streams.
Generalized section of the sedimentary rocks of the Devils Tower National Monument.
The talus extends from high on the shoulders of the Tower down to and across the sedimentary rock.
About 1,400 feet north of the Tower are two patches of what is believed to be talus formed from sedimentary rocks that once surrounded the Tower.
At the time of its intrusion it was surrounded and probably covered by several hundred feet of sedimentary rock.
Devils Tower owes its impressiveness to its resistance to erosion as compared with the surroundingsedimentary rocks, and to the contrast of the somber color of the igneous column to the brightly colored bands of sedimentary rocks.
The Tower is believed to have been formed by the intrusion of magma into the sedimentary rocks, and the shape of the igneous mass formed by the cooled magma is believed to have been essentially the same as the Tower today.
Following this, the Black Hills area was repeatedly uplifted, and erosion exposed the older sedimentary and intrusive rocks.
These sedimentary rocks, which overlie much older rocks (Precambrian), were deposited in a series of successive layers during time intervals from the Cambrian period to well into the Tertiary period.
The Pyrenees are the upcurled lips of the huge limestone sea-bed, that at some vastly remote period was snapped from east to west, and through the fissure thus formed the granite was thrust, lifting along with it the sedimentary rocks.
It exhibits a vast and elevated tract of horizontal and sedimentary strata, extending for hundreds of miles north and south.
Another method is to calculate how long it would take to form the sedimentary rocks, like sandstones and mudstones, which have a total thickness of over fifty miles, though the local thickness is rarely over a mile.
The weathering of the high grounds of the ancient crust by air and water furnished the material which formed the sandstones and mudstones and othersedimentary rocks, which are said to amount to a thickness of over fifty miles in all.
Much of the material of the original crust has thus been broken down and worked up again many times over, and if the total thickness of the sedimentary rocks is added up it amounts, according to some geologists, to a total of 67 miles.
When the exposed land consists of several unlike formations, sedimentary and igneous, the denudation produces changes proportionably more heterogeneous.
Considering the perishable nature of many of the lower organic forms, the metamorphosis of many sedimentary strata, and the gaps that occur among the rest, we shall see further reason for distrusting our deductions.
That the oldest known sedimentary rocks have been greatly changed by igneous action, and that still older ones have been totally transformed by it, is becoming undeniable.
And the fact that sedimentarystrata earlier than any we know, have been melted up, being admitted, it must also be admitted that we cannot say how far back in time this destruction of sedimentary strata has been going on.
The proximity to nearby oil- and gas-producing sedimentary basins suggests the potential for oil and gas deposits, but the region is largely unexplored.
We find also in many parts of the Highlands of Scotland long valleys, nearly level, which are filled with incoherent sedimentary deposits, and bounded like the lochs by steep mountains.
All observations concur in showing that the fossil floras and faunas differ from the present animal and vegetable forms the more widely in proportion as the sedimentary beds to which they belong are lower, or more ancient.
It is indisputable that many millions of years, probably thirty or forty, must have elapsed while the great sedimentary rocks were being deposited.
Owing to local peculiarities at the mouths of rivers, accumulations of sedimentary matter take place in the middle of the stream, dividing it into two or more branches.
Little sand and clay show in the lime rock of this period, before the marshes of the Carboniferous Age took the place of the ancient inland sea of the Subcarboniferous Period, the sedimentary accumulations of which we are now talking about.
Most of the stratified and sedimentary rocks, but not all, may be included under this term.
Five per cent, of ash may be reasonably expected in pure coal, unmixed with sedimentary deposits.
The Archean of the Vermilion district of Minnesota comprises the Soudan formation, an altered sedimentaryseries with banded cherts, jasper and magnetite schists; the iron ores are extensively mined.
The presence of carbonaceous shale and graphitic schists as well as of the altered sedimentary iron ores has been taken as indicative of vegetable life.
There are districts in which are found short fissures, generally confined to certain horizons in sedimentary rocks, such as the limestones of the great Mississippi Valley, from which are mined lead and zinc ores.
This would be the case with ores that occur in sedimentary beds, for instance, where it is advisable to have the mining plant centrally located so as to work expeditiously the entire area.
Such a body of ore must be in a sedimentary series of rocks.
This being the case, the study of the petrology of the igneous rocks is necessary, in order to arrive at a true understanding of the composition of the sedimentary ones.
In the above passage the terms igneous rock and sedimentary rock have been used, and it is necessary to give some account of the sense in which they were used.
Again, as the bulk of the sedimentary deposits has been formed beneath the waters of the ocean, relics of marine organisms are naturally more useful than those of freshwater ones.
The petrology of the sedimentary rocks is still in its infancy, though much has already been done, but it offers a wide field of inquiry to the field-geologist and worker with the microscope[8].
The upper vessel should also be provided at the top with a loose covering of muslin to serve as a strainer, and this should be replaced at intervals as it becomes clogged with sedimentary matter.
Fill up the vessel with water, and allow some time for sedimentary matter to settle.
Traces of such are to be found only in the sedimentary strata.
The parts of the earth's crust, which the geologists call the sedimentary formations, were not formed all at once.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "sedimentary" in a variety of sentences. We hope that you will now be able to make sentences using this word.
