430 EARTHQUAKE PIIEMOMENA. 



duced, their character and dimensions; whether the level of the sur- 

 face of the sea is, in repose, the same before and after the subsidence 

 of the great sea-wave and its secondary or oscillatory waves; whether 

 any subsequent irregularity of tide occurs after the shock or great 

 sea- waves, or any permanent change of establishment should be ascer- 

 tained. 



As accurate a section as possible of the form of the littoral bottom, 

 beach, offing, and out to deep water, should be got by soundings in 

 the line of the coming in of the wave, and laid down on paper. It 

 should be noticed whether the great wave comes in of muddy or dis- 

 colored water, or clear and like the sea it traversed; and, where 

 possible, a cruise should be made out to sea in the direction whence 

 the waves came, to look for pumice, dead fish, volcanic ashes, or other 

 indications of the distant origin or centre of disturbance. The cotidal 

 lines of the great waves should be laid down in direction upon a map 

 of the coast. 



The secondary effects of the great sea-wave, most worthy of re- 

 mark, are the materials, if any, carried in from deep sea, such as 

 loose mineral matter, new animal or vegetable forms, or the substances 

 swept from off the land and sunk in the depths of the sea. As the 

 range of transferring power of a great sea-wave (wave of translation) is 

 only equal to the wave itself, but little matter will be carried inland 

 from the sea bottom, unless where the depth is great close to shore. 



If fish or testacea are thrown inland into fresh water, the effects on 

 them should be noticed. Lastly, the effects of the passage of the 

 wave over the land and all that stands upon it are to be observed. 

 In recording the transporting power of the wave, (i. e., its absolute 

 transferring power, without reference to distance,) the size, form, 

 specific gravity, and lithological character of rocks or boulders moved, 

 the distance moved and height lifted are to be given; the base on 

 which moved, and if rock, the scratches or furrows produced; the 

 mode of motion, and if swept or rolled along, the obstacles overcome 

 in their progress. Where gravel or loose materials are moved there 

 should be given an estimate of the mass moved, and to what distance; 

 the character, external and internal, of its deposition; the mutual 

 relations or sorting of its fine and coarse parts. The effects on build- 

 ings variously exposed; on vertical and sloping sea-walls; on steep 

 faces of cliffs, and on the caverns excavated in them. The denuding 

 effects of the wave in sweeping off sand, gravel, trees, animals, &c 

 The disruption and lifting of masses and abrasion of stratified rocks, 

 especially of nearly level and nearly vertical beds. Effects of vertical 

 sea-walls or cliffs in the reflection or extinction of the wave. 



Specimens should be taken of the rock of which very remarkable 

 boulders or architectural fragments moved by the wave consist; of 

 any new or strange matters cast up, or gases or vapors evolved from 

 the sea, or ejected from fissures, cavities, wells, &c, on land; of min- 

 eralized or suddenly fouled water found in fissures or wells. Of these, 

 where possible, immediate chemical qualitative examination should be 

 made. 



Such specimens in particular should be brought home of the rocks 



