The broken appearance of the surface of many parts of this country; with the Swallows, as they are called, or basons on some of the mountains, like volcanic Craters, where the rain-water sinks into the earth; and the numerous large stones, which seem to have been thrown over the land by volcanic explosions; as well as the great masses of Toadstone or Lava; evince the existence of violent earthquakes at some early period of the world. At this time the channels of these subterraneous rivers seem to have been formed, when a long tract of rocks were raised by the sea flowing in upon the central fires, and thus producing an irresistable explosion of steam; and when these rocks again subsided, their parts did not exactly correspond, but left a long cavity arched over in this operation of nature. The cavities at Castleton and Buxton in Derbyshire seem to have had a similar origin, as well as this cavern termed Thor's house. See Mr. Whitehurst's and Dr. Hutton's Theories of the Earth.] 95 Broad ponderous piers sustain the roof, and wide Branch the vast rain-bow ribs from side to side. While from above descends in milky streams One scanty pencil of illusive beams, Suspended crags and gaping gulphs illumes, 100 And gilds the horrors of the deepen'd glooms. --Here oft the Naiads, as they chanced to play Near the dread Fane on THOR'S returning day, Saw from red altars streams of guiltless blood Stain their green reed-beds, and pollute their flood; 105 Heard dying babes in wicker prisons wail, And shrieks of matrons thrill the affrighted Gale; While from dark caves infernal Echoes mock, And Fiends triumphant shout from every rock! ---So still the Nymphs emerging lift in air 110 Their snow-white shoulders and their azure hair; Sail with sweet grace the dimpling streams along, Listening the Shepherd's or the Miner's song; But, when afar they view the giant-cave, On timorous fins they circle on the wave, 115 With streaming eyes and throbbing hearts recoil, Plunge their fair forms, and dive beneath the soil.-- Closed round their heads reluctant eddies sink, And wider rings successive dash the brink.-- Three thousand steps in sparry clefts they stray, 120 Or seek through sullen mines their gloomy way; On beds of Lava sleep in coral cells, Or sigh o'er jasper fish, and agate shells. Till, where famed ILAM leads his boiling floods Through flowery meadows and impending woods, 125 Pleased with light spring they leave the dreary night, And 'mid circumfluent surges rise to light; Shake their bright locks, the widening vale pursue, Their sea-green mantles fringed with pearly dew; In playful groups by towering THORP they move, 130 Bound o'er the foaming wears, and rush into the Dove.