# Memoir on the Island of Navassa (West Indies)/Concluding Remarks

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VIII.—Concluding Remarks.
In another publication, "the Island of Navassa illustrated" from my sketches, a topographical map and five views complete the description of the general features and appearance of the Island. In this Memoir I have endeavored by a discussion of its topographical, lithological and geological characters to demonstrate its economical importance.
Its formation as an elevated coral island has been first discussed.
The characters of those islands, so interesting to the progress of natural sciences, have but recently been the object of study and publications of eminent geologists, and the record of all facts bearing on this subject is still needed to confirm or perfect the theories of those great observers.
The facts elicited at Navassa will be found valuable, as bearing on the following questions of so great interest to geology:
The formation of hard compact limestone in modern ages, and still going on under our eyes, by the work of zoophites.
​Additional proof of the phenomena of subsidence and elevation of lands; the regularity and horizontality of the strata at Navassa, and the absence of traces of all violent disturbances, showing that such elevation may have taken place, as Sir Ch. Lyell and other geologists have demonstrated in other cases, without volcanic action.
The soundings made around the Island by Capt. E. K. Cooper, of Baltimore, (who first discovered the existence there of phosphatic guano, and was the owner of the Island before the organization of the present company,) prove anew that elevations may be formed under the level of the sea by the action of currents and the accumulation of sands to afford a foundation to the construction of the corals, other than submerged volcanic peaks. These soundings establish that all around the Island there are the following depths, commencing at Lulu Bay, on the southwest side of the Island, and found on circumferences:
Those depths indicate that the rocks of Navassa are built on an elevation, with a gentle declivity, the formation of which does not require for its explanation, volcanic action; but may have been formed, as an island in the bed of a river, by the action of the currents in the channel between the older islands of Hayti and Jamaica. The description of Navassa shows its uniformity of character with the other islands of the same origin; presenting the same remarkable peculiarities of a shore platform and numerous caves.
As a consequence of those analogies, results the probability of finding fresh water by digging wells, a discovery of so much economical importance for the working of those vast deposits of phosphatic guanos.
The formation of those deposits of phosphates of lime originating from organic matters modified, indurated and mineralized by the protracted action of atmospheric influences, show how mineral masses have been formed by the accumulation of ​organic matters, as exemplified by the microscopic researches of Ehrenberg and others.
From the mode of formation of Navassa, and the facts that I have mentioned, there is good ground to admit that the deposition of phosphate has been going on since the Island was elevated above the level of the sea, filling all the cavities of the coralline limestone. This leads to the conclusion, in my opinion, that those deposits are of great depth, increasing in value by their freedom of foreign matters as it was announced by Dr. G. A. Liebig, in his report on the Island, and subsequently demonstrated by his numerous analyses and chemical studies of the Navassa guano.
G. Bischof, in his treatise on Chemical Geology, has said:
"There is perhaps no instance in which the influence of organized structure upon minerals is shown to a greater extent than in the circulation of phosphoric acid. Plants are the true collectors of this acid. They increase its quantity in uncultivated soils where the subsoil contains phosphates, or where those salts are supplied by water."
This remarkable action of the plants on the collection of phosphoric acid proves its importance for the life of vegetation, and the consequent necessity to supply it from other sources when exhausted by crops. It explains also the lasting benefit to the amelioration of soils afforded by the appliance of phosphatic fertilizers; all parts of this indispensable substance, the phosphoric acid, being collected by the organism of vegetation.
Many times in passing over the celebrated battle field of Waterloo during the summer months, more than thirty years after the bloody conflict, I had occasion to remark vast clusters of luxuriant wheat, rising high above the common level, showing by its height, its vivid color, the strength of the straw, the length and weight of the heads, the places where large accumulations of human or other bones deeply buried beneath the soil, did supply year after year by their successive decomposition, the soluble phosphoric acid absorbed, and I might say sucked by the plants.
So lasting must be the influence on the crops of the fertilizers manufactured with the Navassa phosphate after the early and powerful action of the soluble phosphoric acid, resulting ​of the partial conversion of the phosphate into super-phosphate has been exhausted.
This action of the phosphoric acid, aided by the addition of a due and limited proportion of ammoniacal salts, cannot be over estimated for fertilizing purposes, and the economical importance of the deposits of Navassa, so interesting as a field of scientific observations, will be readily understood by the rare occurrence of so valuable a material in extensive mineral deposits.
However large may become the profits accruing to the Navassa Phosphate Company by the working of so valuable a property, none will be more legitimate, none will be better justified by corresponding returns of agricultural wealth.