CAVATINA 



174,064; (1881) 129,476; (1891) 111,679, of whom 



"i were Catholics, and 16,325 Episcopalians. 

 ) \\ \N, the county town, stain Is on a branch of the 

 Amialee, s." miles NW. of Dublin by rail. It has 

 acourt-hoiise and a grammar -school ; an<l the beau- 

 tiful demesne of Lord Fainliain lies between 'avail 

 ami l.i.iiL;li < 'ii'Jii'-i , which is ahout 5 mile.s west. 

 l'..|.. al.out : 



CAVE 



33 



4'avali na, a short fonn of operatic air, of a 

 smooth and melodious character, differing from the 

 ordinary aria in consisting only of one part, and 

 frci|iimtly appearing as part of a grand scena. 

 Examples of i avat ina are found in many well- 

 known operas, as Sunniiiiilniln and Les Huguenots. 

 The term is also often used for a complete air or 

 song, such as the ' Salve dimora ' in 



Cave, or CAVERN (Lat. cavus, 'hollow'). The 

 natural hollows which occur in and underneath 

 rocks have originated in various ways some being 

 due to the chemical and mechanical action of 

 water, others to dislocations and disruptions pro- 

 duced by movements of the crust, or .by superficial 

 rock-falls and landslips, while yet others are tunnels 

 which now and again occur in or under thick sheets 

 of lava. Caves formed by marine erosion are fre- 

 quently met with along the coast- line of Britain and 

 other countries, Fingars Cave at Staffa (q.v.) being 

 a splendid example. They are not confined to any 

 particular kind of rock although, other things 

 Ming equal, they are of course more easily formed 

 in readily yielding rocks than in more durable kinds. 

 It is ratner the character of their natural division- 

 planes or beds and joints than their composition 

 and texture that determines whether the rocks at 

 the base of a sea-cliff shall be hollowed out or not 

 by the action of the waves. If the rocks are thin- 

 bedded and abundantly and regularly jointed, it is 

 obvious that as soon as any portion is undermined 

 by the sea, the overlying masses will immediately 

 yield along their division-planes and topple down. 

 If, on the other hand, the rocks are meagrely and 

 irregularly jointed, and occur in massive beds, then 

 they will not so readily collapse when undermined, 

 and caves will tend to be formed. Caves which 

 have had this origin are not uncommonly met with 

 along the line of old sea-margins in many regions 

 which have been elevated in recent geological 

 times. Most frequently, however, the entrances 

 to such caves are concealed by the rock-rubbish 

 which has been detached from time to time by the 

 action of the weather from the cliffs above. 

 Caves of erosion are also formed by river-action 

 at the base of crags and cliffs in many valleys. 

 And now and again such hollows may be detected 

 at various levels in river-cliffs, as if they had been 

 formed during the gradual excavation of the ravines 

 in which they occur. 



In Britain and other countries long occupied by 

 man most of such river-cliff caves or rock-shelters 

 have been artificially deepened and widened, and 

 this to such an extent that it is often hard to 

 say how much of the work can be attributed to 

 nature. By far the most important caves, how- 

 ever, are those which owe their origin to the 

 action of underground water. But before these are 

 described, mention may be made of the hollows 

 which occur now and again in and under lava- 

 Hows. Where lava has flowed over and solidified 

 above a mass of snow and ice, the subsequent 

 melting of the latter will leave a hollow behind. 

 Near the Casa Inglese, on the south-east side of the 

 highest cone of Etna, a mass of ice of unknown 

 extent and thickness, covered by lava, was seen 

 by Lyell in 1828 and again in 1858. But this, 

 it must be remembered, is at a height of 10,000 

 feet above the sea. In lava itself, however, 

 caves of considerable extent occur. Many of 

 107 



these are simply great blisters or hollows formed 

 by the expansive power of the highly heated 

 vapours contained in the lava at tin- tiim- of it* 

 eruption. ( Mhe.ru again may have been caused by 

 tin- sudden conversion into steam of the water of 

 lakes or streams suddenly overwhelmed by a lava- 

 How the steam thus generated might either 

 violently rupture the lava by its explosive force, or 

 produce great tunnels and irregular cavities under 

 the liquid lava, already inclosed in its solid crust, 

 by pressing it upwards. The extensive Fossa 

 del la Palomba of Etna is supposed by some to have 

 had such an origin. But probably the greater 

 number of the larger caves under lava have been 

 formed by the escape of the lava itself from its own 

 solidified envelope. When lava pours out from a 

 volcanic orifice it very rapidly coagulates above 

 and below, so that the liquid rock becomes im- 

 prisoned in a hardened crust of its own material. 

 The great pressure of the inclosed lava, however, 

 upon the crust at the terminal point of the flow 

 suffices again and again to rupture it, and the lava 

 then flows out freely until it is again imprisoned in 

 the same manner. In the case of very liquid lavas 

 this escape is often completed in a perfect manner 

 and a long underground tunnel is left liehind, 

 from the roof of which depend long stalactites of 

 black glassy lava. Extensive caves formed in this 

 way some of them measuring over 100 feet in 

 width occur in the Azores, the Canary Islands, 

 Iceland, and other volcanic regions. 



Another class of caves embraces such hollows 

 as have originated during earthquakes or other 

 movements in the crust of the earth. At such 

 times rocks are rent asunder, and when they fall 

 rudely together irregular cavities are left between 

 the disjointed masses, and similar results often 

 take place when great landslips occur. But the 

 most extensive caves and underground galleries 

 have been excavated by the chemical and mechan- 

 ical action of underground water. Sometimes 

 these hollows continue more or less persistently 

 in one direction,' but most usually they wind 

 tortuously about, and often open into similar 

 intricate galleries, which, in like manner, com- 

 municate with lateral extensions of the same char- 

 acter. There can be no doubt that caves of this 

 kind are the channels of underground streams and 

 rivers, and that they have been excavated, in the 

 first place, by the chemical action of acidulated 

 water making its way downwards from the surface 

 along the natural division-planes of the rocks, 

 untileventually space has been licked out for the 

 passage of a subterranean stream. The cavities 

 would then tend to be enlarged by the filing action 

 of the sand and gravel which the underground 

 stream and its numerous feeders might sweep 

 along. Many such underground watercourses are 

 well known at the present day, and the direction 

 of some of them can be traced by the swallow-holes, 

 chasms, and 'sinks,' which indicate places where 

 the roofs of the cavities have given way, or have 

 been pierced by the action of acidulated water. In 

 certain regions almost all the drainage is thus con- 

 ducted underground rivers after flowing for a 

 considerable distance at the surface suddenly dis- 

 appear, and follow a hidden course, for it may be 

 many miles, before they emerge again to the light 

 of day. Sometimes, indeed, they never come to 

 the surface again, but enter the sea by subterranean 

 channels. Should anything occur (such as earth- 

 quakes, &c. ) to interrupt such a system of under- 

 ground drainage, and the streams and rivers be 

 compelled into new channels, the old subterranean 

 courses will then become galleries more or less dry. 

 which may be accessible by one or even by several 

 openings. 



As it cannot be doubted that all such great 



