Metamorphic rocks are such as were originally stratified, but afterward underwent a change of structure through the agency of heat or chemical action.

Veins are rock-matter filling the cracks of fissures of other rocks. They vary greatly in size and extent. They may be regular or irregular in form, isolated or united in a complex network.

The term drift is employed to designate the immense deposits of sand, gravel, clay and boulders, or loose rocks, which exist over a great part of the American continent. The origin of this material is referred to " Glacial Period," when, from some cause, a change of climate caused immense masses of ice, either in the form of icebergs or glaciers, to plow their way over the continent, bringing the material from the Archæan beds and depositing it over the existing formations, and at the same time scoring and grooving the underlying rocks.

The Geologic Ages.

There are seven great geologic ages, or divisions of time, known as the Azoic, the Silurian, the Devonian, the Carboniferous, the Reptilian, the Mammalian, and the Age of Man. Our knowledge of the plants and animals of the ages preceding the creation of man is derived from their remains dug out of the earth, and called fossils.

The Azoic Age is the era, as its name implies, when there was no life, either vegetable or animal, on the globe. The crystalline minerals and all the igneous rocks date back to this age, and hence they are destitute of fossils.

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During the Silurian Age, the second in atiquity, there was no terrestrial life; but mollusks-animals with soft, fleshy bodies, without any internal skeleton, like the oyster and the snailabounded in the waters. The oldest sandstone and limestone. belong to this period. Its plant-fossils are sea-weeds.

The Devonian Age was the age of fishes, remarkable for their thick, bony scales. The sea also teemed with shells, corals and sea-weed; while the land, though yet limited in extent, began to be covered with vegetation. Insects, the earliest of terrestrial animals, now first appeared.

The Carboniferous Age, or age of coal, is fourth. From colossal tree ferns, leaves and branches, deposited in successive centuries, were formed, by gradual decomposition under water, those vast coal-beds on which the industrial pursuits of the present day so largely depend. The animals of this age consisted mainly of insects of various kinds; and inferior tribes of reptiles.

The Reptilian Age was marked by the great number, variety and size of its reptiles, the appearance and habits of which are known from the remains, found buried in the rocks of this period. The rocks of this age are the freestones, extensively used for building, sandstone formations, intersected with ridges of trap of igneous origin, limestone and gypsum, laminated and plastic clays, and chalk-beds, containing layers of flint.

The Mammalian Age was the sixth. The reptiles now dwindled in size and diminished in number, being succeeded by quadrupeds, some of which were much larger than any modern species. The deinotherium, mastodon, megatherium and fossil

elephant were among the gigantic animals of this era, while the plants resembled those of the present time, palms, oaks, maples, magnolias, etc., being found in the forests.

The Age of Man is the last of the seven geologic ages. The huge monsters that gave the preceding period its peculiar character became extinct, and were replaced by smaller animals - those we see around. Man was created, and invested with dominion over the earth. This is the "era of the finished world-the era, also, of man's progress and preparation for another and a higher life."

THE EARTH'S SURFACE.

The earth's surface of an area of about 197,000,000 square miles, of which only about one-fourth is land.

Lowlands are tracts, either level or diversified by hill and vale, not elevated more than 1,000 feet above sea-level. Deserts are extensive tracts destitute of water, and, consequently, of vegetation and animal life.

Silvas are forest plains. Plains that produce grass, but not trees, are known in North America as prairies; in South America as llanos and pampas; in Asia and Southeastern Europe as steppes.

The desert of Sahara, as far as known, consists partly of table-lands and partly of low plains. It is interspersed with oases, or fertile spots, which are generally lower than the surrounding country; some of these are of considerable extent and well populated.

A mountain is an elvation of land exceeding 2,000 feet in height. A hill is less than 2,000 feet in height.

A mountain-chain is a long, elevated ridge, or several mountains extending in a line.

Mountains are of great use to man. They attract the clouds, condense their moisture, and store up in reservoirs the water received from them, sending it forth again in streams, from thousands of springs, to fertilize the soil. They increase the surface of the earth, giving variety to its vegetable productions. They protect the adjacent countries from cold and piercing winds, and thus exert a favorable influence on their climate.

An avalanche is a large mass of snow, icc and earth, sliding or rolling down a mountain. A water-shed is the mountainchain or ridge of land which separates one basin from another, and from which the rivers flow.

A mountain pass is an elevated road crossing a mountainchain through a natural opening or depression.

Glaciers are immense masses of ice formed by the accumulated snows upon the mountain tops. They fill in vast valleys, and have an onward motion throughout like a liquid or semiliquid body, Their course down the slopes is very slow, but, like rivers, they flow faster in the middle than at the bottom and sides. The lower extremities are constantly melting, forming torrents and mountain streams, while the upper parts are fed by the snows. Rocks of immense size are torn off and carried down by glaciers. They occur in the greatest numbers in the Alps. When a glacier reaches the ocean large fragments are broken off and float away as icebergs.

VOLCANIC PHENOMENA.

That the interior of the earth has a high temperature, independent of the influence of the sun's rays, seems to be proven by many phenomena. The majority of scientists maintain that the center of the earth is a mass of molten material, and that consequently the temperature increases the nearer this center is approached. This theory seems to accord with the facts in relation to hot springs, artesian wells, volcanoes, etc., although it is maintained by some that these phenomena may be caused entirely by local chemical changes going on within the earth's

crust.

Hot Springs.

Thermal or hot springs are most common in mountainous regions, and especially where the earth's crust is most broken and disturbed. Springs of every kind are formed by the rain or melted snow sinking into the earth and issuing from it again at a lower level. The fact that the water is sometimes hot, shows that it must have come in contact with heated rock material within the crust of the earth.

They are found of every grade of temperature from that of slightly above the surrounding atmosphere, to the boiling point. They are found in all parts of the world, the most numerous, perhaps, in Europe.

Geysers

Are intermittent, spouting, hot springs, and have a temperature at the boiling point. They are found in Iceland, New Zealand, and in the "National Park" at the head waters of the Yellowstone River in the Rocky Mountains.

The most celebrated is the Great Geyser of Iceland. It consists of an immense well, or funnel, 10 feet wide at its mouth, and about 70 feet deep, surmounted at the surface with a basin 65 feet in diameter and 7 feet deep, formed by the deposit of mineral matter from the water. At intervals it sends up a column of water and steam to the height of 100 feet. More remarkable even than the geysers of Iceland are some that are found in the "National Park." One, the Giantess, throws water to the height of 200 feet. Grasshoppers and other insects, and pieces of wood which fall into the waters, soon become incrusted with quartz, which is held in solution by the water, thus permanently petrifying them.

Volcanoes.

A volcano is a mountain, or opening in the earth's crust, through which issue fire, smoke, ashes, lava, steam, etc. Volcanoes may be distinguished as extinct and active. Extinct volcanoes are such as are now at rest, but were subject to eruptions in former ages, as is shown by their form and structure, and the presence of craters. Active volcanoes are such as are either in a constant state of eruption, or have eruptions from time to time, with intervals of rest.

Volcanoes throw out an enormous amount of material. Whole islands and portions of continents have been formed by volcanic action. Iceland is an example of a volcanic island.

The lava, when it first issues from a volcano, is somewhat like melted iron running from a furnace, but soon cools on the surface

and forms a black, porous crust. Sometimes the streams are so thick that the interior remains hot for twenty years.

A terrific eruption of Mt. Vesuvius, A.D. 79, destroyed the flourishing cities of Pompeii, Herculaneum and Stabiae, and covered them with ashes and cinders to the depth of fifteen feet.

About sixty eruptions of Mt. Etna are recorded. In 1669, a stream of lava from this mountain overflowed the ramparts of Catania, sixty feet in height, and destroyed a portion of the city. In 1832, several craters opened in the sides of the mountain, and a stream of lava eighteen miles long, one mile broad, and thirty feet deep, poured over the adjacent fields.

In 1835, the terrible eruption of Conseguina occurred. It lasted three days, during which the light of the sun was obscured over half of Central America, and more than 40,000 square miles are said to have been covered with dust, ashes and lava.

Fields of Fire.

In some localities an inflammable gas issues from openings in the ground. This gas frequently becomes ignited and burns for some time. There is a region of this kind on the western shore of the Caspian Sea. This gas is supposed to be from the decomposition of vegetable matter by internal heat.

Earthquakes.

The second class of volcanic phenomena are earthquakes. These consist of vibrations or tremblings of the earth's crust, and are caused by movements in the fluid interior; but how these movements are produced, is as yet unknown. It is estimated that since the Creation earthquakes have destroyed thirteen million human beings. Scientists assert that not less than twelve shocks of earthquake are experienced in the United States daily, although, of course, they are but slight, and individually unworthy of mention.

An earthquake is generally preceded by unmistakable signs. The electrical condition of the air seems to be changed perceptibly to both men and beasts-the former experiencing oppression and dizziness; the latter uttering cries of distress, running wildly about, or otherwise manifesting uneasiness. The atmosphere is unnaturally still and hazy, and the sun seen through it looks like a ball of fire.

The year 1868 was remarkable for the number and severity of its earthquakes. One of these occurred in the Sandwich Islands, destroying whole villages and many lives. One of the most terrible earthquakes on record occurred in South America, in August of that year. Its center of activity seems to have been at Arica, a seaport of Peru, which was completely destroyed, with two hundred of its inhabitants. The shocks extended throughout the Andes, from the United States of Colombia to Chili, and towns and cities were laid in ruins. It is estimated that more than fifty thousand persons lost their lives by this catastrophe.

The great earthquake of Lisbon occurred November 1, 1755. A rumbling sound beneath the surface was immediately followed by three shocks, so close together that they seemed but one, which threw down the principal part of the city; the sea

retired, leaving the bar dry, and instantly returned in a wave forty feet high, engulfing a great marble quay, to which multitudes had fled to escape the falling buildings. In the space of six minutes, thirty-five thousand persons perished.

The most remarkable earthquake that has occurred in the United States is that of New Madrid, on the Mississippi, in 1811-12. For several months there was an incessant quaking of the ground, which, for a distance of three hundred miles, rose and sank in undulations. The most of the town was submerged.

Readers will remember the earthquake which visited Java in 1882, and also that in Spain the latter part of December, 1884, the shocks continuing into the middle of January, 1885. According to the official record, the number of persons killed in Granada was 695, while 1,480 were injured.

The crust of the earth is in some places gradually and slowly rising; in other places it is sinking. The coast of North America, from Labrador to New Jersey, is slowly rising. The southern part of Greenland is sinking. The Scandinavian peninsula is sinking in the southern part and rising in the northern part. These changes are at the rate of a few feet only in a hundred years. The cause is probably the slow contraction from cooling of the earth's crust.

ISLANDS.

About one-seventeenth of the land surface of our planet is in the form of fragmentary bodies, called islands. They may be considered as of two classes: Continental, those lying in the near vicinity of the continents, and really forming a part of the continental structure, and oceanic, those lying at a distance from the continents, in the midst of the oceans, and differing in structure from the continents.

Oceanic islands are all small and usually occur in groups. Their rock structure is essentially different from that of the continents, and the vegetation and animal life generally peculiar. They may be divided into two classes-volcanic, or high, and the coral, or low.

The volcanic islands are the summits of active or extinct volcanoes projecting above the water. They are usually considerably elevated, with steep shores, and more or less circular in outline. Some have peaks of great height, as one of the Sandwich Islands, with the peak of Hawaii, fourteen thousand feet above the sea level. Many of them have appeared within the history of man.

Coral islands are among the most interesting phenomena of Physical Geography. They owe their existence to the work of colonies of small radiate animals called polyps. The structure of the polyp consists of a cylindrical or sack-like membrane, attached at the bottom to some solid body, and enclosing a second sack, which forms the stomach. At the top is an opening, or mouth, which is surrounded by thread-like organs called tentacles. When expanded, the polyp resembles a flower in form and often in the beauty of its color. The solid coral, which composes the reef, is secreted in the cavity between the outer and inner membranes, as the bones are secreted in the

bodies of higher animals. Coral polyps multiply by eggs, to a certain extent, but chiefly by a process of budding similar to the branching of plants. Thus they grow into vast communities, in which generation succeeds generation, each individual leaving behind, as it dies, its contribution to the reef in the form of a small cell of carbonate of lime. The polyps cannot live out of water, and hence their work must cease at low water mark. Fragments of the coral structure are broken off and thrown upon the top of the mass by the waves, and thus in the course of time a reef, as it is called, is formed, projecting from the water. Upon this reef a vegetation finally springs up from the seeds which the winds and waves bring, and a soil is formed from the pulverized coral, drifted material and decayed vegetation. The reef-building polyps exist only in tropical regions, or where the water never gets below the temperature of 68° F.

WATER.

This all-important and ever-present liquid is a chemical combination of two gases, oxygen and hydrogen-eight parts of the former by weight being combined with one of the latter. When pure, it is destitute of color, taste and smell; but, as it readily absorbs gases and dissolves many solids, it is seldom found in this state.

The large body of water covering by far the greater part of the earth's surface is called the ocean. There is really but one ocean; but the continents partially divide it into five basins, which we distinguish by different names, as the Atlantic, Pacific, Indian, Arctic, and Antarctic Oceans.

The bottom of the ocean is supposed to be diversified with depressions and elevations-with low plains, plateaus and mountains-like the land; hence the depth differs in different parts. Some of the researches lately made by English explorers in regard to deep-sea beds have, however, led to the belief that there are no rough ridges, abrupt chasms nor bare rocks, and that the sea bottom, at great depths, is not affected by currents or streams-even by those of the magnitude of the Gulf Stream -its general appearance rather resembling that of the American prairies, and it is everywhere covered by a kind of mud. The greatest depth shown by soundings is eight and three-quarter miles. The mean depth of the whole body of the ocean is estimated at four miles.

The color of the ocean is a beautiful sky-blue where the depth is great, but in shallow water, yellowish tints, reflected from the bottom, mingle with the blue, and produce a grayish green.

Phosphorescence, one of the most beautiful of marine phenomena, is a brilliant light occasionally observed in the sea during dark nights, particularly in tropical regions. Sometimes the crests of the waves, the spray thrown up by the ship's bow, and the wake she leaves behind, look as if they were on fire. This phenomenon is produced by myriads of animalcules, which have the property of emitting light from their bodies, like fire-flies. A hundred of them have been found in a single drop of sea-water.

The Oceanic Movements.

The great body of the ocean is never at rest; not only is the surface agitated by the winds, but even at great depths the water moves from one region to another.

There are four oceanic movements, viz.: waves, tides, currents and whirlpools.

Waves are ridges of water, produced by the friction of winds on the surface. Tides are alternate risings and fallings of the waters of the ocean.

Tides are produced by the attraction of the moon and sunprincipally that of the former-acting with different degrees of force on different parts of the earth. Were the moon the sole cause of the tides, they would always be of the same height; but the sun also exerts an attraction, which, according as it acts with or against that of the moon, increases or diminishes the height of the tide.

The currents are vast streams which traverse the ocean, and keep its waters in perpetual circulation. The principal of these are the Gulf Stream, the Equatorial, Japan, Antarctic and Arctic

currents.

The Gulf Stream.

The most important of the oceanic currents is the Gulf Stream, so called from the Gulf of Mexico, out of which it flows into the Atlantic, through the Strait of Florida. It is from twenty-five to one hundred and fifty miles in width, and moves with a velocity of from one and one-half to five miles an hour, the water being much warmer than other parts of the ocean near it. Its color is of a deep indigo blue, strikingly different from the green of the surrounding ocean. A branch of this vast body of warm water, constantly flowing past the western coast of Europe, exerts a most genial influence on the climate. Even many miles in the interior the air is tempered by west winds, warmed by contact with this great stream. The Gulf Stream carries the heat of the Caribbean Sea across the Northern Atlantic to the shores of Scotland and Norway. This tropical river, flowing steadily through the cold water of the ocean, rescues England from the snows of Labrador. Should it, by any chance, break through the Isthmus of Panama, Great Britain would be condemned to eternal glaciers.

The Equatorial Currents.

An equatorial current crosses the Atlantic from the coast of Africa to the neighborhood of Cape St. Roque. It there divides into two branches, a northwesterly and a southwesterly, each of which follows the South American coast-the former making its way into the Caribbean Sea and the Gulf of Mexico.

In the Pacific two equatorial currents are found-one north and the other south of the equator. The former, turning to the northeast near the Loo Choo Islands, continues under the name of the Japan current. The south equatorial current of the Pacific consists of two branches, one of which, striking the Australian coast, divides into a northwesterly and a southwesterly branch, as does the Atlantic equatorial current on the coast of Brazil; the other, farther north, turns near the Caroline Islands, and reverses its course, crossing the Pacific again in a

direction nearly due east to South America, under the name of the Equatorial counter-current.

The Japan Current,

In the Pacific, bears a remarkable resemblance to the Gulf Stream in the Atlantic. Impelled by the Pacific equatorial current, it sweeps from the China Sea along the Asiatic island chains, in a northeasterly direction, toward the Aleutian Islands and Alaska, the climate of which it improves, as the Gulf Stream does that of Northwestern Europe. Between the Japan current and the main land, a cold current sets in the opposite direction, as in the case of the Gulf Stream.

The Antarctic Current,

Which enters the Atlantic, runs in a northwesterly direction to the southern extremity of Africa, and thence along its western coast until it joins the Equatorial near the Gulf of Guinea. That which sets into the Pacific flows along the South American coast, under the name of the Peruvian or Humboldt current, and is merged in the Equatorial west of the Gulf of Guayaquil. The Antarctic current, belonging to the Indian Ocean, runs along the western coast of Australia, and unites with the Equatorial just north of the Tropic of Capricorn.

From the Arctic Ocean two cold currents set to the south, one on each side of Greenland. Uniting at the mouth of Davis Strait, they continue their southerly course as far as Newfoundland, where part of this broad Arctic river, as an under-current, flows beneath the Gulf Stream, and the rest, as a surface-current, keeps inside of this stream, close to the American shore as far south as Florida.

Whirlpools are circular currents, which occur in certain localities.

Inland Waters.

The inland waters of the earth are springs, rivers and lakes. The rain or melted snow and hail which sinks into the earth, penetrates the crust until it reaches an impervious strata, when it runs along until it finds an outlet at the surface in the form of a spring, or gathers into underground reservoirs, some of which, by their peculiar formation, having an outlet in the form of a siphon, form intermittent springs.

The drainage from the surface and the water from springs form small streams which unite to form rivers. When the water from streams and from the surface collects in depressions on the earth's surface, it forms lakes.

Lakes may be divided into classes, as follows: (1) Those having inlets, but no visible outlets. (2) Those having outlets, but no apparent inlets. (3) Those having no apparent outlets or inlets. (4) Those having both inlets and outlets.

The Caspian Sea, Aral Sea and Great Salt Lake are examples of the first class. Such lakes are usually salt. The water is either all lost by evaporation or is absorbed by the earth. Lakes of the second class are usually found in mountainous regions, and are the source of some large rivers. The water evidently comes from springs and rises until it runs over the basin. Lake Albano, near Rome, is an example of the third class. Such lakes are usually situated in elevated regions, are supposed to be

the craters of extinct volcanoes, and are fed by springs. Lakes of the fourth class are by far the most common.

When water evaporates, all impurities are left behind; hence rain water is not salt like the ocean. The water of springs, rivers and lakes is, therefore, pure and fresh, unless it comes in contact with foreign matter that it is capable of dissolving.

THE AIR.

The earth is surrounded by an elastic fluid called air, which enters the minutest pores, and therefore exists in every substance.

Air, like everything else, is attracted by the earth, hence it has weight, although experiments show that it is 815 times lighter than water.

Air is essential to the transmission of sound, to combustion, and to life.

CLIMATE.

Climate is the state of the atmosphere in regard to temperature, winds, moisture and salubrity.

The climate of a place as regards temperature depends upon : Latitude.-The general law is that the amount of heat is greatest at the equator, and diminishes toward the poles. There are three reasons for this: 1. The sun's rays fall perpendicularly upon the earth at the equator, and more and more obliquely as we go toward the poles. 2. The area covered by a given amount of heating power from the sun is smaller at the equator. 3. Where the sun's rays fall perpendicularly they pass through a less amount of atmosphere, and the absorption of heat is less.

Altitude. The decrease in temperature is about three deg. F. for every 1,000 feet of elevation. As the air receives most of its heat by radiation and reflection from the earth, and as the higher we go the less dense the air, the less heat is absorbed either from the earth or from the direct rays of the sun.

Prevailing Winds.-Winds blowing from the tropical regions carry the heat with them, and conversely, winds from the polar regions lower the temperature. Whichever wind prevails throughout the year in a given place will consequently modify the temperature of that place.

Length of Day.- During the day the earth receives from the sun more heat than it radiates into space; while during the night it radiates more than it receives. Hence a succession of long days and short nights results in an accumulation of heat, raising the average temperature and producing summer; while long nights and short days result in a temperature below the average, producing winter. The heating power of the sun is greater in summer, because at that season it is shining more directly upon that part of the earth, and conversely in winter. In the tropical regions the inequality of day and night is very little, but increases toward the poles. The temperature in the tropics is therefore more uniform. The length of day makes up for the lessened intensity of the sun's rays; hence a place in high latitude may have at times higher temperature than a place within the tropics.

Ocean Currents.-The warm waters of the tropical regions being brought toward the polar regions bring the heat with them, radiating it into space, and it is absorbed by the atmosphere.

Mountain Ranges.-A mountain range will make a country near it warmer or colder, according as it shields it from a cold or warm wind. The Distribution of Land and Water.- Land heats or cools rapidly, absorbing or emitting but little heat. Water heats or cools slowly, absorbing or emitting large quantities of heat. Hence the land is subject to great and sudden changes of temperature; the water to small and gradual changes. Places situated near the sea have, therefore, a more equable climate.

Character of Soil.- Dry, sandy soil heats and cools more rapidly than wet and marshy lands; hence the latter will have a more uniform temperature.

Slope of Land.— Land which slopes so that the sun's rays will strike it nearer vertically will receive more heat. The south side of a hill is warmer in winter than the north side.

In regard to winds the climate of a place depends upon: Temperature.-As winds are but masses of air set in motion by the unequal heating, the winds of any given place depend primarily upon the temperature, though not necessarily upon the temperature of that place. As the air is heated in the tropical parts of the earth by the sun, it rises, and colder air flows in from the polar regions to take its place; hence the primary currents, which are modified in various ways by other causes.

Rotation of the Earth.-The winds are turned out of their course by the rotation of the earth in the same manner as the ocean currents.

Land and Water.- The land becomes warmer during the day than the sea, and, the air rising, a cooler air flows in from the sea. At night the land parts with its heat more rapidly than the water and becomes cooler; then the wind sets the other way. Hence we have the land and sea breezes.

Elevation of the Land.- Mountains, as has already been stated, shelter places from winds. Some of the great plains are subject to almost constant winds.

In regard to moisture, the climate of a place depends upon : Prevailing Wind.- If a wind blows from large bodies of water in a warm region it will be laden with moisture which will be likely to be precipitated on reaching a colder country.

Mountains.-The contact of a moisture-laden wind with the cold sides of mountains will cause a precipitation of its moisture, and the regions beyond the mountains will not receive it.

Forests, by shading the earth, keep its surface cool, and this tends to condense the moisture.

Cultivation of the Soil, causing it to absorb moisture from the atmosphere, and by capillary attraction in dry weather bring up moisture from below to the surface.

Temperature.- Increased heat causes greater evaporation, and hence more moisture in the atmosphere. More rain falls within the tropics than in the temperate or polar regions.

Land and Water.- More rain falls on the coasts of a country than in the interior, because the winds are more moist. More rain falls in the northern hemisphere than in the southern because there is a greater diversity of land and water, the evaporation coming mainly from the ocean, and the condensation from the diversified land surface.

Isothermal lines are lines connecting places that have the same mean temperature.

There is a line or limit of elevation, above which the surface is covered with perpetual snow; this is called the snow line.

WINDS AND WEATHER.

Wind is air in motion. Winds have a purifying effect upon the atmosphere; they dissipate unhealthy exhalations; they transport vapors from the sea to moisten and fertilize the land; they carry the seeds of plants far and wide, and thus extend the empire of vegetation; finally, they waft our ships, and are, in some countries, made available as a motive power for machinery. The cause of winds is the difference of heat received from the sun in different places. The heated air expands, becomes rarefied, and rises. The cooler air immediately rushes in from the surrounding parts, to restore the disturbed equilibrium.

The trade-winds are so named because, by their regularity, they favor commerce. They are produced as follows: The equatorial regions being most intensely heated, a current of rarefied air is there constantly ascending, while colder currents from the north and south set in toward the equator to fill its place. When these reach the ascending current, having in turn become rarefied, they follow it in its upward course, and thus air is withdrawn from the higher latitudes, and accumulated in the equatorial regions.

Whirlwinds are bodies of air that have a rotatory or spiral motion, and are usually caused by the meeting of contrary winds.