ON THE FACTS OF BARTHQUAKE PHZ NOMENA. 51 
%; 
every day upon a smaller, where the sides of hollow ways, having been 
‘undermined by rain-waters, are detached into the bottom by their own 
weight ;” or he might have added, shaken down by anything causing vibra- 
tion, as the passage of a waggon or cart. 
3rd. New valleys are also hollowed out. 
Not only are they hollowed out gradually, as above, by the erosion of newly- 
formed river-courses, but they are made at once by the slipping of vast 
masses of soil. Thus, along the bases of the hills, says Dolomieu, referring 
to those above the great plain along the whole length of the chain, the soil, 
which adhered to the granite of the bases of the mountains, Caulone, Esope 
Sagra, end Aspramonte, slid over the solid nucleus, the inclination of which 
is steep, and descended, leaving almost uninterruptedly from St. George to 
beyond Christina, a distance along the base of the hills of nearly ten miles, a 
chasm between the solid granite nucleus and the sandy soil of the plain. Thus 
ΟΠ avalley was formed of great length in a moment, parallel to the mountain 
sides and below them; but this cut off the drainage of the mountain slopes 
_ from the plain, and hence in after years the ridge of debris forming one side 
of the valley would become cut through and traversed by streams and torrents 
descending to the plain, dividing it into isolated masses of hills, and soon de- 
_ stroying all recognition of its singular mode of formation. 
_ A ravine was measured by Grimaldi, which was formed nearly a mile long, 
105 feet wide, and 30 feet deep, in*the district of Plaisano; another was 
ae at Cerzulle, three quarters of a mile long, 150 feet wide, and 100 
eet deep; and one at La Fortuna about a quarter of a mile long, 30 feet 
wide, and 225 feet deep; and various others are mentioned which it is need- 
4 __ less to detail here. 
᾿ς Without enlarging the list, “ what is said will be sufficient to demonstrate,” 
_ says Dolomieu, ‘that the singular circumstances attendant on the earthquake 
were the natural effects of a violent shock acting on a sandy ground pre- 
_ viously opened and torn by torrents.” “The general effect was, that of 
heaping together the soil, establishing slopes where there were before steep 
__ escarpments, disconnecting masses that had bases insufficient for their bulk, 
- only supported by lateral adherence, and of filling interior cavities.” 
__ These landslips, had they occurred in land reposing upon hard rock, such 
_ as clayslate or granite, and more especially if the deep beds of clay already 
contained pebbles and boulders of hard stone, would in their progress have 
_ furrowed and grooved the subjacent rocks, and left thereon permanent traces 
of their movements, that would have presented to a geologist, thousands of 
_ years after, all the aspects of ice or glacier action, and where no other grounds 
_ to suspect earthquake origin existed, would probably have been set down to 
_ these causes. 
Let us remark here the vast difference in effects that these secondary phe- 
_ by valleys and rising into mountain crests. How different would be the 
_ effects in our own country of a great earthquake that should shake at once 
the London basin, and ‘all the eastern side and south of England, and the 
Isle of Wight with the mountains of North Wales, and the Grampians! 
Wight, how utterly would its surface and geology be changed in a day; 
what changes on the face of the cultivated banks of the Severn, the Thames, 
_ the Medway, to say nothing of our brick-built cities! Yet how different from 
the effects in Snowdonia and the Grampians! Here, or in any such regions 
E2 
