Word Finder - strata

definition

One of several parallel horizontal layers of material arranged one on top of another.

synonyms

• tier

definition

A layer of sedimentary rock having approximately the same composition throughout.

synonyms

• bed
• layer

definition

Any of the regions of the atmosphere, such as the stratosphere, that occur as layers.

definition

A layer of tissue.

definition

A class of society composed of people with similar social, cultural, or economic status.

definition

A layer of vegetation, usually of similar height.

definition

The level of accuracy of a computer's clock, relative to others on the network.

Marsh, who, after 1870, discovered a great number of bird remains in the Cretaceous strata of North America.

In the lower strata were discovered the remnants of Cyclopean or prehistoric architecture already mentioned.

Its congeners even then lived in England, as is proved by the fact that their relics have been found in the Stonesfield oolitic rocks, the deposition of which is separated from that which gave rise to the Paris Tertiary strata by an abyss of past time which we cannot venture to express even in thousands of years.

The mountains are composed in great part of Paleozoic strata, often modified by vulcanism and greatly denuded and sculptured by wind and water erosion.

The successive " Minoan " strata, which go well back into the fourth millennium B.C., reach down to a depth of about 17 ft.

There are four formations of Cretaceous strata in Mississippi, defined by lines having the same general direction as the one just described.

Seven formations (or groups) of the Tertiary strata have been distinguished in Mississippi.

It is, indeed, as if the high land of central Asia had been pushed southward against and over the unyielding mass formed by the old rocks of the Indian peninsula, and in the process the edges of the over-riding strata had been crumpled and folded.

There were, moreover, other and broader oscillations which raised or lowered extensive areas withbut much crumpling of the strata, and to these are due some of the most important breaks in the geological series.

A region where volcanic activity has led to the embedding of dykes or bosses of hard rock amongst softer strata produces a plain broken by abrupt and isolated eminences.'

Over the greater part of the Cambrian country the strata are still nearly as flat as when they were first laid down, and the deposits, even of the Cambrian period, are as soft as those of the Mesozoic and Tertiary formations in England.

Such lakes (in common with all the plateau hamuns of south-west Baluchistan and Persia) change their form and extent from season to season, and many of them are impregnated with saline deposits from the underlying strata.

In the Carboniferous strata (Coal measures) remains of Hexapods become numerous and quite indisputable.

In the south-east of Bosnia the predominant formations are Triassic and Palaeozoic strata with red sandstone and quartzite.

The steep icewalls at the margin of the inland ice show, especially where the motion of the ice is slow, a distinct striation, which indicates the strata of annual precipitation with the intervening thin seams of dust (Nordenskidld's kryokonite).

Beds of this age, consisting of sandstones and coal, are found on the northern coast of Disco Island and the southern side of the Noursoak Peninsula, the beds in the former locality, " the Kome strata " of Nordenskiold, being the oldest.

Still, the presence of dicotyledonous leaves, such as Magnolia alternans, in the Atanakerdluk strata, proves their close alliance with the Dakota series of the United States.

Undue stress is often laid on the fact that Lingula has come down to us apparently unchanged since Cambrian times, whilst Crania, and forms very closely resembling Discina and Rhynchonella, are found from the Ordovician strata onwards.

C. White, of the U.S. Geological Survey, who found strata of fairly good coal at depths of 100 to 200 ft.

That it results from the weight of the overlying strata.

Although petroleum wells in Russia have not the depth of many of those in the United States, the disturbed character of the strata, with consequent liability to caving, and the occurrence of hard concretions, render drilling a lengthy and expensive Drilling in operation.

The highest strata (Volcanic group) form the rugged elevated spurs of the Drakensburg mountains which extend along the eastern territorial boundary.

The Trilobites are known only as fossils, mostly Silurian and prae-Silurian; a few are found in Carboniferous and Permian strata.

The genus Agnostus, which belongs to the last category, occurs abundantly in Cambrian strata and is one of the earliest forms A known.

These chapadas and elevations, which are usually described as mountain ranges, are capped by horizontal strata of sandstone and show the original surface, which has been worn away by the rivers, leaving here and there broad flat-topped ridges between river basins and narrower ranges of hills between river courses.

A considerable part of it has been excavated by these rivers to a level which gives their valleys the elevation and character of lowlands, though isolated hills and ranges with the characteristic overlying horizontal sandstone strata of the ancient plateau show that it was once a highland region.

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.

Pre-Darwinian zoologists had been aware of the class of facts thus interpreted by Fritz Muller, but the authoritative view on the subject had been that there is a parallelism between (a) the series of forms which occur in individual development, (b) the series of existing forms from lower to higher, and (c) the series of forms which succeed 'one another in the strata of the earth's crust, whilst an explanation of this parallelism was either not attempted, or was illusively offered in the shape of a doctrine of harmony of plan in creation.

In the latter range a few Ordovician fossils have been found, but in general the oldest strata which have yielded organic remains belong to the Cretaceous system.

The contorted strata of slate and greywacke rock must have been formed at a period vastly anterior to that in which the lake of the upper valley managed to force an outlet through the enclosing barriers.

All the strata intersected by the Rhine between Bingen and Bonn contain fossils of the same classes.

The shape of the hills and ridges is necessarily influenced by the inclination of the strata, by the relative hardness of different rock-beds, and by the presence of folds and fissures and other lines of weakness.

A quartz vein or bed of hard rock may show itself as a sharp ridge or as a well-defined bench; a stratum of soft rock or the line of a great fissure, or the weakening of the strata by an anticlinal fold, may produce a ravine or a deep valley.

A tunnel differs from a drift in that it is driven across the strata to intersect the deposit.

Drifts and inclined shafts following the deposit may prove difficult of maintenance when the workings become large and settlement of the overlying strata begins.

Rock-filling yields and becomes consolidated under heavy pressure, and therefore does not furnish a rigid support of the overlying strata, but rather a cushion to control and equalize the subsidence.

Above, the ground has been completely worked out from the surface, and the space formerly occupied by ore is now filled with the debris of the overlying strata which has caved in above the block of ore now being worked.

The special difficulties which attend deep mining, in addition to the problems of hoisting ore and raising water from great depths, are the increase of temperature of the rocks and the pressure of the overlying strata.

Intrusions of a serpentine-like rock break through the Miocene strata north of Bhamo, and similar intrusions occur in the western ranges.

At a time when the Cartesian system of vortices universally prevailed, he found it necessary to investigate that hypothesis, and in the course of his investigations he showed that the velocity of any stratum of the vortex is an arithmetical mean between the velocities of the strata which enclose it; and from this it evidently follows that the velocity of a filament of water moving in a pipe is an arithmetical mean between the velocities of the filaments which surround it.

He considered the horizontal strata of this hyperboloid as always in motion, while the remainder of the water was in a state of rest, and imagined that there was a kind of cataract in the middle of the fluid.

He supposed that the surface of the fluid, contained in a vessel which is emptying itself by an orifice, remains always horizontal; and, if the fluid mass is conceived to be divided into an infinite number of horizontal strata of the same bulk, that these strata remain contiguous to each other, and that all their points descend vertically, with velocities inversely proportional to their breadth, or to the horizontal sections of the reservoir.

The geological formation of the soil belongs to the Quaternary and Pliocene period in its upper strata, and to the Eocene and Cretaceous in the lower.

The oldest strata, consisting of gypsiferous marls, are referred to the Muschelkalk and show an alternation of lagoon with marine conditions.

The Central Cordillera consists mainly of crystalline and volcanic rocks, on each side of which are aqueous, in great part Jurassic, strata thrown up almost vertically.

The whole range is highly auriferous, and the thickness of the strata is not less than 10,000 ft.

Before the object can pierce the dense lower strata of air its material is usually exhausted, but on rare occasions it withstands the fiery ordeal, and fragments of the original mass fall upon the earth.

The Cyclostomata are numerous in Palaeozoic rocks, but attained a specially predominant position in the Cretaceous strata, where they are represented by a prpfusion of genera and species; while they still survive in considerable numbers at the present day.

On the other hand, limestone and sandstone, especially of the Mesozoic strata, are strikingly deficient.

In the western Carpathians the inner zone consists of a foundation of Carboniferous and older rocks, which were folded and denuded before the deposition of the succeeding strata.