100 



PROCEEDINGS OP THE ACADEMY OP 



Eumont a village ia the department of LaMeurthe, the earth of which was very 

 ferruginous, two arm bones of a female, a cubitus and a radius, having a deep 

 bluish green color. On breaking, the alteration was found to be complete, and a 

 qualitative chemical examination proved it to be phosphate of iron. It is to be 

 regretted that a quantitative analysis was not made, to have determined whether 

 all the bone phosphate had been decomposed and the transformation into phos- 

 phate of iron complete. M. Nickles, on examining the medullary cavity with a 

 lens, found among the sinuosities left by the hardened marrow brilliant points 

 which were distinctly crystals of vivianite. The bones were in a perfect state 

 of preservation, and afforded, when treated with hydrochloric acid, a skeleton 

 of gelatine, proving that gelatine does not resist the absorption of the ferrugin- 

 ous compound. 



Various theories have been formed and published as to the origin of the rock 

 guano ; these are most likely premature, as the accounts as to its occurrence are 

 founded on reports of those not accustomed to noting geological phenomena. 

 The continued and gradual upheaval of islands in the ocean and their depression 

 is a well established geological fact. 



The islands of the Caribbean sea are very varied, some are quite low and 

 covered with sand composed of fragments of shells, madrepore and corals, 

 which can readily be distinguished with a pocket lens. These sands are resorted 

 to by myriads of waterfowls for laying their eggs. One of the captains who 

 visited there mentions, that it is necessary to make one's way through them 

 with a stick. Other islands attain heights of 800 feet ; it seems improbable 

 that such heights could be created by accretions of guano and sand, when the 

 islands were subject to a continued action of the waves of the ocean. The in- 

 clination and irregularity of the guano layers renders it not improbable that 

 the dynamic causes which produced this distortion, elevated at the same time 

 the islands. 



It is most probable that the guano rock from some of the islands has been 

 changed in its composition by reactions of the salts contained in sea water, but 

 before such reactions can be fully explained, accurate analyses must be made of 

 this sea water. 



It is a remarkable fact, that the composition of the ash from the recent guano 

 from the heights of the Centinellarock composed of phosphates of alumina and 

 iron, should have a composition so very near to that of the guano rock 

 from the Los Monges and El Roque islands. 



The frequent occurrence of alumina and iron is to be remarked in the guano 

 rocks. 



The upheaval and subsidence of land is caused not only by earthquakes, 

 (Lyell's Principles of Geology, 8th edit. chap, xxxi.,) but by other changes such as 

 are in progress in Sweden and Norway, and in Greenland. The upheaval of islands 

 in the Caribbean Sea may most likely be ascribed lo volcanic action, some of 

 these are within 150 miles from Gaudaloupe. (Lyell's Principles, 33G,) von 

 Buch inclined to the belief, that the volcanic chain of the Andes was connected 

 with that of the West India or Caribbean Islands. The truth of this conjecture 

 has been almost set at rest by the eruption of the volcano at Zamba, in New 

 Grenada, at the mouth of the river Madalena.* 



The vicinity of the volcanoes may give additional salts to the sea water. 



Note. — I have just been informed by Dr. Luther, that from analyses lately 

 made in Baltimore of a cargo of rock guano, that has lately arrived from the 

 island of Testigoes, there has been found from forty to forty-five per cent, of 

 phosphoric acid. 



*Comptes Rendus, 1849, vol. xxix. p. 531. 



[March; 



