STRUCTURE OF THE TURKS ISLANDS 265 



from observations made in 1770 in the Sir Edward Hawke, King's 

 Schooner." Further details are given in Note 32 of the Appendix; 

 but I may say here that it represents the results of a regular survey, 

 the three main positions being fixed by astronomical observations, 

 the error in longitude being about forty minutes and the errors in 

 latitude not exceeding two miles. But, as will be noticed below, 

 when discussing the effects of the reclaiming process in these islands, 

 the period for comparison is very limited, since the latest Admiralty 

 chart of this group is mainly based on the survey of 1830. It is, 

 however, permissible to infer on grounds given in the Note that 

 there has been extensive shoaling between the islands since the 

 French survey, though the depths on the open bank clear of the 

 islands experienced but slight change in the interval between the 

 middle of the eighteenth and the middle of the nineteenth century. 

 Lesser Sand Cay, a sandy islet lying between Cotton Cay and Grand 

 Turk, on which plants obtain at times a scanty hold, evidently did 

 not exist at the time of the French survey. 



The Degradation of the .ZEolian Sandstone in the Turks 

 Islands. — Just as L. Agassiz in the case of the seolian rocks of the 

 islands of the Salt Key Bank lays stress on the extensive disintegra- 

 tion they are experiencing at the hands of the atmospheric and 

 marine agencies, so we may lay emphasis on the same process of 

 destruction in the Turks Islands. If Nature busied herself in pro- 

 ducing these deposits ages ago, she is not doing so now. There is 

 nothing about these formations that is modern. For ages they have 

 been exposed to great degradation; but, as we shall see, Nature by 

 setting up a reclaiming process is now doing her best to save the 

 pieces. In those localities where there is no protecting beach, as in 

 the case of the smaller rocky cays and of some of the headlands of 

 the larger islands, the full force of the breakers of the open ocean 

 is spent in the destruction of the seolian sandstone. Long narrow 

 rocky islands, such as Long Cay and Penniston Cay, where there is 

 no protection against the breakers, have already been cleft through 

 near their extremities. Toney Rock, which lies near Eastern Cay 

 and receives the whole brunt of the breakers, represents the last 

 stage in the process of destruction. When a beach protects the 

 coast, the atmospheric agencies are active in degrading the cliff- 

 faces that once were buffeted by the waves. The bluffs, so con- 

 spicuous on the eastern side of Grand Turk, are from this cause in 

 full retreat landwards. 



The Modern Process of Reclamation of Land from the Sea 

 in the Turks Islands. — As already observed, A. Agassiz lays no 

 stress on reclaiming agencies in the Bahamas. L. Agassiz, who 

 rightly includes the Salt Key Bank in the Bahamian region, refers 

 to the " very instructive combination of the phenomena of building 

 and destruction " in its shoals and keys. In the Turks Islands 

 there exists, side by side with the process of degradation of the 

 original land-surface of seolian rock, a process of renovation that 

 will ultimately prevail. It is unfortunate that a comparison of the 

 old French chart of 1753 with that in present use covers too short a 

 period to be of much service to us. The Admiralty chart (No. 1441) 



