CURRENTS OP THE SEA. 191 



successively formed seaward from the old, what dug up the 

 sediment which formed the old, and lifted it up from where 

 specific gravity had placed it, and carried it out to sea over a 

 barrier not more than a few feet from the surface ? Indeed, Sir 

 Charles himself makes this majestic stream to tear up its own 

 bottom to depths far below the toiD of the bar at its mouth. He 

 describes the Mississippi as a river having nearly a uniform 

 breadth to the distance of two thousand miles from the sea.* He 

 makes it cut a bed for itself out of the soil, which is heavier than 

 Admiral Smyth's deep sea water, to the depth of more than two 

 hundred feetf below the top of the bar which obstructs its en- 

 trance into the sea. Could not the same power which scoops out 

 this solid matter for the Mississippi draw the brine up from the 

 pool in the Mediterranean, and pass it out across the barrier in 

 the Straits ? The currents which run over the bars and shoals 

 in our rivers are fed from the pools above with water which we 

 know comes from depths far below the top of such bars. The 

 breadth of the river where the bar is may be the same as its 

 breadth where the deep pool is, yet the current in the pool may 

 be so sluggish as scarcely to be perceptible, while it may dash 

 over the bar or down the rapids with mill-tail velocity. Were 

 the brine not drawn out again from the hollow places in the seg,, 

 if w^ould be easy to prove that this indraught into the Mediter- 

 ranean has taken, even during the period assigned by Sii' Charles 

 to the formation of the Delta of the Mississippi — one of the 

 newest formations — salt enough to fill up the whole basin of the 

 Mediterranean with solid matter. Admiral Smyth brought up 

 bottom with his briny sample of deep sea water (six hundred 

 and seventy fathoms), but no salt crystals. 



389. Views of Admiral Smyth and Sir C. Lyell, — The gallant 

 admiral — appearing to withhold his assent both from Dr. Wol- 

 laston in his conclusions as to this under current, and from the 

 geologist in his inferences as to the eff'ect of the barrier in the 

 Straits — suggests the probability that, in sounding for the heavy 

 specimen of sea water, he struck a brine spring. But the 



* " From near its mouth at tlie Belize, a steam-boat may ascend for two thou- 

 sand miles with scarcely any perceptible difference in the width of the river." — 

 Lyell, p. 263. 



t " The Mississippi is continually shifting its course in the great alluvial plain, 

 cutting frequently to the depth of one hundred, and even sometimes to the depth 

 of two hundi-ed and fifty feet"— Lyell, p. 273. 



