18 IN LOWER FLORIDA WILDS 



Some time after this mid-Pleistocene elevation 

 there came a second subsidence, but only of a few 

 feet. Along the low, rocky bluffs in and just 

 north of Cocoanut Grove, erosion marks made by 

 the surf are plainly visible. The same evidences 

 may be seen in the great hammock south of 

 Miami, its eastern rocky wall having been the sea- 

 shore at the time of this slight subsidence. Now 

 the southern end of this wall is quite a distance 

 back from the bay though at the Punch Bowl 

 the bluff comes out to the shore. The same 

 erosion marks may be seen on a bit of rocky bluff 

 on the north side of Little River, and along the 

 walls of Arch Creek. There are old beaches on 

 which long dead (but specifically recent) sea shells 

 are scattered, in several places back from the 

 western shore of Biscayne Bay and again at Boca 

 Raton, north of Fort Lauderdale. These are six 

 or seven feet above tide and correspond in height 

 with the surf marks on the bluffs near the Punch 

 Bowl. A similar shell beach on Big Pine Key 

 of the lower chain, would indicate that the sub- 

 sidence was not so great there, as it lies about 

 three feet above the ocean. These old beaches 

 mark the limit of the second subsidence and during 



