1870.) 223 [Shaler. 



Physical Geography of the Phosphate Region. 



The physical geography of the area occupied by the phosphate 

 beds is so important, not only to a proper understanding of the his- 

 tory of their formation, but also to a right appreciation of their 

 economic value, that it will be well to set it forth briefly before Ave 

 consider the beds themselves. 



The coast of the United States between the parallels of 25° and 

 35° north latitude, forms a shallow and very regular westward curve. 

 The depth of this bight is about two hundred miles, and the width of 

 the opening measured from Cape Hatteras its northernmost, to Cape 

 Florida its southernmost point, is not far from six hundred miles. 



The land which bounds this great indentation is quite level for a 

 distance of some tens of miles from the shore, rarely rising more than 

 seventy five feet above the tide level within this belt. The character 

 of the shore along this great Bay of the Carolinas x varies very remark- 

 ably, considering the little variety of vertical relief found there. 

 From Cape Hatteras southward for a distance of about two hundred 

 miles, the shore is bordered by a peculiar series of low islands, dis- 

 posed in the fashion of a barrier reef. Along this whole shore the 

 sands which comprise the outer islands seem to be in constant move- 

 ment, the gaps between the islands changing their positions from year 

 to year. The observations of the Coast Survey have given very 

 valuable data for the study of these peculiar reefs, but it is not nec- 

 essary for us to examine their history. South of Cape Fear we pass 

 beyond this system of barriers and come upon a section of shore 

 which differs in no important regard from the usual type of low shore 

 on which the sea is slowly gaining. This second section of the Bay 

 of the Carolinas has a length of about one hundred miles, extending 

 from Cape Fear to Cape Roman. The whole coast from Cape Hat- 

 teras to Cape Roman forms three great indentations. The northern- 

 most of these, sometimes known as Raleigh Bay, is entirely formed 

 by the narrow ridge of the sand reef which separates the ocean from 

 the broad water of Pamlico Sound. Immediately on the south of 

 Raleigh Bay lies Onslow Bay, which shows along the whole coast line 

 the same structure which we find in Raleigh Bay, but somewhat less 

 distinctly. South of the southern point of this Bay we find less and 



1 Not being able to find any name for this remarkable feature of our continent, 

 I have ventured to give it this one, in order to avoid the difficulties arising 

 from the want of designation. 



