INTERIOR LAND CHANGES. 425 



as it was of their destruction, would not all observers say, and have not all actually said 

 Here are the works of man, his temples, his houses, furniture, and personal ornaments ; 

 his very wine and food ; his dungeons, with skeletons of the prisoners chained in their 

 awful solitudes, and here and there a victim overtaken by the fiery storm ? Because the 

 soil had formed, and grass and trees had overgrown, and successive generations of men 

 had erected their abodes over the entombed cities, and because these were covered by lava 

 and cinders, still does any one hesitate to admit that they were once real cities ; that 

 they stood upon what was then the surface of the country ; that their streets once rang 

 with the noise of business ; their halls and theatres with the voice of pleasure ; and that 

 they were overwhelmed by the eruptions of Vesuvius, and their places blotted out from 

 the earth and forgotten? These inferences no one can dispute all agree in the 

 conclusions to be drawn. When, moreover, the traveller sees the cracks in the walls of 

 the houses of Pompeii, and observes that some of them have been thrown out of the 

 perpendicular, and have been repaired and shored up with props, he infers that the fatal 

 convulsion was not the first, and that these cities must have been shaken to their foundation 

 by the effects of previous earthquakes. In like manner the geologist reasons respecting 

 the physical changes that have taken place on the surface of our globe. The crust of the 

 earth is full of crystals and crystallized rocks ; it is replete with the entombed remains of 

 animals and vegetables, from mosses and ferns to entire trees from the impressions of 

 plants to whole beds of coal. It is stored with the remains of animals, from the minutest 

 shell-fish to the most stupendous reptiles. It is chequered with fragments, from fine sand 

 to enormous blocks of stone. It exhibits in the materials of its solid strata every degree 

 of attrition ; from the slightest abrasion of a sharp edge or angle, to the perfect rounding 

 which produces globular and spheroidal forms of exquisite finish. It abounds in dislocations 

 and fractures; with injections and filling up of fissures with foreign rocky matter; with 

 elevations and depressions of strata in every position, from the horizontal to the vertical. 

 It is covered with the wreck and ruin of its former surfaces ; and, finally, its ancient fires, 

 although for a while dormant, have never been wholly extinguished, but still find an exit 

 through volcanic mouths. When we reflect upon these phenomena, we cannot hesitate to 

 infer that the present crust of the earth is the result of the conflicting energies of 

 physical forces, governed by fixed laws ; that its changes began from the dawn of the 

 creation, and that they will not cease till its materials and its physical laws are anni- 

 hilated." 



The mass of matter ejected from many volcanoes, whether lava, stones, or ashes, has 

 frequently been of gigantic magnitude, adding thick layers of material to the surface of 

 the country over which the currents have streamed, and upon which the showers have 

 fallen. Vesuvius, in 1737, gave out a stream of lava, which passed through Torre del 

 Greco to the sea, and contained upwards of 33,587,058 cubic feet; and in 1794 a lava 

 current pursued the same course, its solid contents amounting to 46,098,766 cubic feet. 

 In 1669, Etna gave forth 93,838,950 cubic feet ; and the sand and scoria? formed the 

 Monte Rossi near Nicolosi, a cone two miles in circumference, and about 450 feet high. 

 The lava contained in two currents from the Skaptar Yokul in Iceland in 1783, which 

 was so hot twelve months afterwards as to be impassable, has been subjected to the 

 following calculation. " Assuming the average breadth of the first current as six 

 miles, and of the second as three, both probably below the truth, the one would cover 

 300 square miles, the other 120, or 420 in all. With an average depth of fifteen yards, 

 the combined mass would contain 429x3097600x15 = 19,514,880,000 cubic yards, or 

 nearly twenty thousand millions. But this comprises only that portion which flowed into 

 the inhabited district, whilst it is likely that an equal or greater quantity remained heaped 

 up around the crater, or flowed off into the unknown regions of the interior. To this must 



