46 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



going on in the Everglades by the action of rain water, and of the forma- 

 tion of the huge sinks which characterize that part of the southern 

 extremity of Florida. He has, I think, suggested the manner in which 

 we may imagine the great sounds like Key Biscayne Bay and Card's 

 and Barnes Sounds to have originated. To this we must, I suppose, 

 add the disintegrating effect of the action of the sea, as soon as a reach 

 of any extent has been formed for the waves. "With the prevailing 

 northeasterly winds, the action of the sea must be very marked. 



The outlets of the northern part of Key Biscayne Bay (Plate XIII.) 

 are numerous, many of them broad passages. There is a wide pass be- 

 tween Soldier Key and the Ragged Keys, as well as passages between 

 these keys and Sands and Elliott Keys. On each side of Soldier Key 

 extends a broad sand bank, leaving ample room for the outlet of the 

 waters of the western part of Key Biscayne Bay east of Elliott Key. 

 Between Soldier Key and Cape Florida there ai*e no less than ten deep, 

 narrow cuts, kept open by the sweep of the tides, with from five to seven- 

 teen feet of water. Still farther to the northward, Bear Cut, which sepa- 

 rates Key Biscayne from Virginia Key, is a comparatively broad passage, 

 over half a mile wide, with from five to seventeen feet of water. On the 

 north side of Virginia Key a narrow passage affords the northernmost 

 outlet of the waters of Key Bisca3"ne Bay. 



The amount of the material which is brought by the outgoing currents 

 on the outer banks of Key Biscayne Bay is seen not only in the sand 

 bores to the northward of Soldier Key, towards Cape Florida, but also 

 in the delta of Caesar's Creek (Plate XIV.), a deep cut separating Elliott 

 Key and Old Rhodes, which is the principal outlet of the southern part 

 of Key Biscayne Bay. Through this cut pours all the material held in 

 suspension or solution in the waters of the western part of Key Bis- 

 cayne Bay. The creek is no less than three fathoms deep in parts, and 

 runs in a bed of its own making nearly two miles out at right angles to 

 the trend of the keys. The creek occupies the eastern edge of a trian- 

 gular bank ; the eastern slope of the bed of the creek is very abrupt, 

 falling in a short distance, varying not more than from 200 to 300 

 feet, into ten feet of water, while its western slope runs very gently to 

 the same depth on a slope a mile in width. The current of the creek 

 has excavated a narrow bed, from seven to eight feet below the general 

 level of the sea face slope of the keys, with a channel of from twelve to 

 eighteen feet of water. The narrowness of the bank on the east side is 

 perhaps due to the damming up of the overflow on that side by the 

 prevailing easterly winds. A similar deposit on a smaller scale is formed 



