to be competent to arrest

Naturw. Classe der Kaisei Burberry Outlet Online 4 Akade®' Bande xxxv.. s. 511. and the latter has been already described where occurring locally in having cut off the town of Diano, from the shock, from north to south through the Diano. Fart li.. d. 330.The ocrt"wence of the second condition, viz.. great lines of dislocation where the fissure first opened, has to a great depth and lor a considerable thickness, become filled m with loose material,seems, from the results of my observations on this earthquake, at once almost the whole progress of the wave.Its entire volume, or by far the greater portion that arrives at the first surface of contact, or wall of the filledfissure, at a 6, Fig. 345, in the direction burberry sale e burberry sale , is expended in compressing and altering the relative positions, of the clays,gravels, rock fragments, detritus, or whatever other loose and incoherent materials the burberry outlet fissure contains. Upon the width of the fissure, in proportion to the amplitude of the wave, at its entering the loose material at a b9 and upon the degree of looseness, incoherence, and capability of being crushed and moved, possessed by the latter, will depend the residual unextinguished portion, that shall be transmitted on to the opposite wall of the fissure c d, and so into and on through, the solid rocks beyond. Where at the same time the rock at both sides, has been so tilted, that its bedding is vertical, and nearly parallel with the walls of the fissure, transverse to the wavepath, then the obstacles to the wave are the greatest possible; and where the plane, or various planes, of the fissure, are met obliquely, by the emergent wavepath, e to , instead of perpendicularly, then we have, in addition to the foregoing, further loss by refraction and reflection, as already described. This effect of fissures, was presented upon a grand scale by the earthquake of December, 1857.Lastly, deep and continuous valleys with precipitous sides, cut off and extinguish the wave at their free lyingsurfaces, upon which the wavepath passes off into free space at their emergent flanks. In this case the portion of the wave that passes on, beneath the bottom of the valley between, and through the lateral flanking range beyond, lies so deep, that its path is not emergent to the surface beyond, until after a distance horizontally, so great, that the energy of the wave is almost expended, or greatly reduced.

the mass of material

The great prevailing positions, of the stratification and bedding of the formations, of the shaken country, whether highly inclined, with generally I different azimuths: or with prevailing horizontal, or gently inclined stratification, extending over great areas.The change of elasticity and density, between the rock of one formation and another, does not, so far as my observation has informed burberry outlet me. produce at all an equal extent of superficial modification, of the wave of shock, to that wmcn is enectea dv tnese iour causes.Breach of burberry sale continuity of medium, as I have long since shown, by the loss of vis mm that takes place at every surface of contact, is the condition, of all the most effective, in limiting the progress of the wave, and robbing it of its volume, up to extinction.From the nature of the building up, of every mountain chain, of antichnals. with strike more or less parallel to its axial line, it follows, that, is most solid, the breaches of continuity, fewest and least, in the latter direction. The wave is therefore best transmitted "end on." by mountain chains ; as well as by the formations reposing on their lowest flanks, and filling the valleys between parallel ranges.Humboldt mentions, that the course of earthquakes in the north of the Asiatic continent and Burberry Outlet Online elsewhere, has been observed u to follow the courses of the great rivers,'' but he offers no explanation of the fact. It is not. however, in consequence of any connection with a river course, that thefact is so. but that the river marks the direction of the great continuous chains, and of the direction also, in which the valley formations are least broken and discontinuous, namely, parallel to the alignment of the flanking chains.The same principles apply, in explanation of the fourth condition stated. The wave travels best " end on to the strata, and not transverse, more or less, to them.When the wavepath is transverse, or obliquely transverse to mountain chains, on the contrary, everything tends to oppose its progress, and hasten its extinction.The surfaces of discontinuity are as numerous, as the multiplied beds that we should cross, m boring through the base of the range, to say nothing of fissures, or other casual breaches of connection.