368 coprolites, is very rich in phosphate of lime; and, although not found The term "marl" having so many and such different significations, dependent upon local usages, as well as the various classifications of scien tific geologists, it is highly desirable that it should be limited to some specific fertilizing material or class of materials, rather than, as now, be made to include deposits as far apart in their chemical constitution and value as in their period of formation. At least, when used, it should be so qualified as to indicate the mineral species to which the substance belongs. The marls of the United States may be divided into argillaceous, glauconitic or greensand, and calcareous. Argillaceous marls are of comparatively little agricultural value, if we consider their chemical constitution only, consisting mainly of clay and sand, with a trifling percentage of lime. There are circumstances, however, as before alluded to, in which they may become true and valuable fertilizers. Glauconitic marls include the greensands of New Jersey, Delaware, and Maryland, and a few localities further south. They are dependent, for their power of permanent beneficial action, upon the potash and phosphoric acid they contain. Full analyses of these deposits will be found in the report of the chemist. Calcareous marls are the débris of countless successive generations of life, the remains of which may or may not be recognizable, according to the amount of pulverization and attrition they have undergone from the motion of the water in which they were deposited, and the subsequent conditions to which they have been exposed. These deposits range in time from the cretaceous epoch of geologists to the present era, and are even now in process of formation both in marine and inland waters. They are found in greatest amount in the tertiary strata. The foregoing account of the origin of marl applies with equal force to most of the limestones. Marls, however, are generally understood to be friable to a considerable extent, and this, together with the fact that many of the marls retain a sensible proportion of organic matter, constitutes a line of distinction between the two. This line is one, however, often hard to draw; for, if it is true that even the hard and crystalline limestones are but the result of various forces, as heat and pressure, acting upon sedimentary strata containing organic remains, it is evident that there may be all grades of consolidation and homogeneity according to circumstances. The physical character of calcareous marls varies with the class of animals, remains of which form their active ingredient, and the state of preservation of the latter; and their agricultural value varies with the proportion of inert matter they contain, and which frequently forms a matrix for the shells and other organic formations. The deposits known as pond marl, or sometimes as shell marl, found in our lakes and ponds, or upon their former sites, and often under peat, explain, by their formation, which may be watched in all stages, the mode of origin of the greater part of the calcareous group. Water containing carbonic acid is, under pressure, a solvent of carbonate of lime, from which the microscopic testaceous animals inhabiting such water, by absorption and secretion, form their shells; and, dying, these are de posited, either to accumulate in vast masses, or, if the water is not sufficiently charged with lime, to be redissolved, reabsorbed, and to sup ply new generations with covering. Any excess of carbonate of lime in the earth is absorbed in the pas sage of the water through it; and thus deposits of this kind form chiefly in limestone regions. In some localities a process similar to the foregoing has caused the formation of large beds of silicious marl, so called. Various species of phytozoa-organisms occupying the border between the animal and the vegetable kingdom, and in spite of many attempts to locate and classify them, not yet definitely assigned to either-possess a shell or skeleton of silica. These accumulate, as in the case of the testacea, and like the calcareous pond marls are both fossil and recent. The beds underlying Richmond, Virginia, are of the former character. Silicious marl, being a fertilizer only in the sense that fine sand is, namely, a physical amendment, will not be further noticed; as it is now believed that all soils contain sufficient silica to supply the wants of plant life, and only require assistance in rendering it soluble. Pond marl, from its friability, minute division, and superficial location, is, in districts where it can be had, the cheapest and best of the purely calcareous manures. It may be applied as extracted or in a calcined condition. In some localities large amounts of this marl are manufactured into lime. The recent calcareous tufa, travertin or calcareous sinter, formed by the precipitation of carbonate of lime direct from its solution in water when exposed to the air, is often called marl. It is, however, a true and pure limestone; and, physically much resembling the pond marl, is for the same reasons a cheap and ready fertilizer. Few States having, as yet, been throughly surveyed with reference to their agricultural and their geological character and economical resources, statistics are necessarily incomplete, and much fuller for some regions than for others of perhaps equal importance. The object of this article, however, being as much to point out deficiencies as to present the results of investigations already undertaken, such information as is accessible will be presented, in the hope that those interested may be induced to communicate more complete and recent information. If the recent discoveries on the southeastern coast may be taken as an indication of what is to follow, the field of research is indeed an inviting one. The older calcareous formations of the Atlantic States constitute a belt of considerable breadth, coinciding nearly with the great eastern mountain chain of the continent, and having numerous offshoots and local outcrops, at greater or less distances from the main range. (See map.) In the eastern States the limestones belong to the so-called Azoic, and to the Lower and the Upper Silurian formations; in other words, the earlier geological ages, The limestone of the Upper Silurian enters Maine from New Brunswick on the northeast; while the same together with the Lower Silurian (Trenton) appears in the mountains of Vermont. Extending along the east line of New York, and approaching somewhat near the coast in northern New Jersey, the limestone belt described passes through Western Virginia, North Carolina, and northern Georgia to its southern limit in northern Alabama. The newer calcareous rocks and deposits belong either to the Carboniferous, the Cretaceous, or the Tertiary formation. The Carboniferous limestone appears in Pennsylvania, and, lying west of and parallel to the Silurian, is traceable to the same distance southwest, occasionally being found in or east of the tract occupied by the older rocks. Limestone of the Cretaceous epoch of the States under consideration is found in Georgia only, the formation being represented further north by the greensand marls. These marls in New Jersey, Delaware and Maryland lie next to the Tertiary, but further inland, and outcrop irregularly, but in a general direction easily traced, through the latter, along the whole Atlantic coast. The Tertiary formation occupies a belt of very gradually increasing width, extending from southern New Jersey to and including Florida, separated from the limestone range by gueiss, slates, and sandstones, over a wide area. In the tertiary are found large and numerous beds of shell-marl and limestone, the latter invariably the result of consolidation and cementation of the former. In these deposits the shells are frequently almost unchanged either in appearance or chemical composition. At many points on the coast is found a still more recent formation, the Quarternary or Post-Pliocene. This is the locality of the South Carolina phosphates. Having thus indicated the general topography and geological character of the mineral fertilizers of the Atlantic States, the specific localities in each State will now be noticed. MAINE. Maine is well supplied with limestone of good quality, and so distributed through the State as to be readily available. With the exception of the calcareous beds of the Lower Helderberg of northern and of eastern Maine, which, as before mentioned, is continuous with that of New Brunswick, the limestone of Maine is of the azoic age, and of crystalline or saccharoid texture. The largest outcrops of this rock are in the counties of Knox and Waldo, and have long been worked for lime, for many years supplying the greater part of the lime used in the eastern States. The convenience of access to the main quarries, those of Thomaston, and the excellence of the lime there manufactured, very early created a large demand, which still continues. The beds lying immediately upon the Keag River, Knox County, are strongly dolomitic. The beds of Waldo County are located in its southern part, and have been largely worked. Numerous small outcrops are found in York, Oxford, and Androscoggin; and in Franklin, Somerset, and Kennebec the beds are not only numerous but extensive. In southern Sagadahock several localities of the rock are reported; also in southern Aroostook and Lincoln, and in Penobscot Counties. In Hancock County the rock, so far as examined, seems to be so altered as to be of little economic value. The Helderberg limestone of northern Aroostook, northern Penobscot, eastern Washington, and central Piscataquis probably underlies a large extent of country, but has not yet been thoroughly examined. This rock has been manufactured into lime to only a limited extent; its product, however, is of good quality. Thorough analyses of the lime-rocks of Maine are not accessible. The percentage of carbonate of lime in a few specimens is as follows: |