PRICE 



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Rio Grande delta areas shows a similar type of profile, smoothly bowed down with scarps at 

 the base. The similarity is striking: one profile is on the hard limestone shelf and the other 

 on a deltaic shelf. This similarity has some implication as to the history of the building of the 

 continental shelf. 



It was seen that the profile from the north Gulf coast at Panama City, east of the Missis- 

 sippi Delta, is also steep and abrupt like the profiles at Corpus Christi and here. These pro- 

 files show a similar characteristic of the continental shelf from west to east, regardless of the 

 type of sediment forming it. 



Figure 9 : Profile off Crystal River Mouth, Florida (going south on the Gulf coast of the 

 peninsula of Florida). This one, off Crystal River, is from the northern third of the peninsula 

 where there is what I call a drowned karst coast and shoreline. You notice again the inshore 

 concave section of the profile. Neither a sandy beach nor a barrier island exists here. The 

 concavity is very low and flat, and there is not a steep jump-off just offshore as seen earlier, 

 only a slightly modified karst plain with some elevations (bars) in the sand zone. 



The land portion of the limestone plain slopes about one and one-half feet per mile. Off 

 shore this slope is one foot to one and one-half feet per mile with the same karst pattern seen 

 through the water as seen on land. Some fathograms show the rolling karst depressions and 

 ridges as expected. Others to the south off the central beach-bordered sector of Florida are 

 nearly smooth showing the karst depressions partly filled. 



The sailing directions say there is not enough sediment in the karst depressions to make 

 good anchoring. Therefore we know that the sedimentation is quite slight, as indicated also by 

 Howard Gould's studies, but there is still much to learn about the character of this shelf and 

 the limestone composing it. 



Figure 10 : Profile off Las Bocas on the western (Campeche) mangrove coast of the 

 Yucatan Peninsula. This profile is similar to that shown for the drowned karst coast of Florida, 

 but it has a coral platform. The small scale of the generalized chart from which the profile is 



Figure 7. 



