Report on the geology of South Carolina

Front matter

U1H OF WM I NDICOTT ft CO S9 B tEKMAN SI N YORK T/^iLtE MEGS oki SMTCi] Bf^Lfl^Al REPORT ON THE GEOLOGY OF SOUTH CAROLINA; BY M. TUOMEY, MEMBER OP THE AMERICAN ASSOCIATION OF GEOLOGISTS AND NATURALISTS — CORRESPONDING MEMBER OP THE NATURAL HISTORY SOCIETY OF BOSTON, AND OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA. COLUMBIA, S. C. PRINTED AND PUBLISHED, FOR THE STATE, BY A. S. JOHNSTON. 1848. To his Excellency, WILLIAM AIKEN, Governor of the State of South Carolina. Sir : — I herewith present a Report on the Geology of the State of South Carolina, and have the honor to be, With profound respect, your Excellency's obedient servant, M. TUOMEY, Geologist to the State. Columbia, Nov. 1846.

Preface

. Geology, Mineralogy and Chemistry, have been long recognized in their relation to Mining, Metallurgy, and some other of the useful arts, but it is comparatively of recent date that these sciences have been applied, systematically and extensively, to the advancement of agriculture and the arts of civilization. Men there were, it is true, who cultivated these sciences, and whose labors were published for the public good — the. journals and transactions of associations for the promotion of science, have furnished those, to whom they were accessable, a vast amount of information applicable to the common affairs of life. But little more than twenty years have elapsed since the first attempt was made by any Government to cause a systematic Geological Survey to be made by competent persons, for the purpose of collecting into a body, for the express use of the people, a correct knowledge of the facts derived from science, in relation to the resources of the territory which they inhabit.

North Carolina* has the merit of having commenced the work ; and, in 182G, a Report upon the Geological and Mineralogical Survey of South Carolina, made by order of the Legis lature, was presented by Mr. Lardner Vanuxem. Since that time, the example of these States has been followed by nearly all the others, so that we have now embodied, in a series of reports, a mass of information on the Geology and industorial resources of the United States, as gratifying to the friends of science as it is useful to the people at large. The Survey, of which the result is contained in the following pages, is due to a movement altogether agricultural. A survey of the State had been long and ably advocated by the late R. W. Roper, Esq. Chairman of the Committee on Agriculture; and, in 1842, an Agricultural Survey of the State was ordered by the Legis lature, and Edmund Ruffin, Esq. of Virginia, whose name and writings are identified with the agriculture of the country, was called to conduct the survey, by Gov.

Hammond. After a year of arduous labor, in the development of the agricultural resources of the State, the result of which is found in his excellent report, Mr. Ruffin resigned, and I had the honor of receiving a commission from Gov. Hammond, to succeed him in conducting the survey. It is difficult, if not impossible, to separate an Agricultural from a Geological Survey — for the science of Agriculture is a combination of all the natural sciences, and whoever examines Mr. Ruffin's Agricultural Report, * I stated in my first annual Report, on the authority of Mr. Vanuxem's report, that South Carolina made the first move ment. This, I have since learned was a mistake.

PREFACE.

. must be struck with the amount of Geological information it contains, particularly as relates to the Tertiary formation of the State. In the renewal of my commission, by his Excellency, Gov. Aiken, in 1844, I was directed .to make a Geological and Agricultural Survey of the State. Such a survey, as it is at present to be understood, includes the following objects. 1 . The determination and description of the various minerals and rocks of the State. 2. Their examination as to extent and relation to each other in their order of superposition, as well as their influence upon the physical features of the State. 3. The discovery of metallic veins, and beds of other useful substances, such as lime, rock, marl, &c. that they may contain. 4. The relations of the rocks to soils, and their chemical examination, to a certain extent. 5.

The pointing out of such improvements in mining and metallurgy, as may be thought useful to those engaged in those operations. While the Natural Sciences form so limited a portion of the systems of instruction in our schools, there will always be difficulty in presenting to the minds of the mass of the people information derived from these sciences. Hence, we constantly hear the objection made to Geological and Agricultural Reports, that they " are too scientific," which only, generally, means that words have been used that are not understood. Now if we speak at all of the constitution of plants, or of rocks, we must use such words as Hydrogen, Oxygen and Carbonic acid — Gneiss, Mica and Hornblende ; nor could any degree of circumlocution obviate the difficulty. Every profession and even every trade has terms technical to itself, yet no one objects to them on this account.

No one finds fault with the art of the miller because he uses such terms as ink, headstock and hopper, although they are quite as unintelligible as any scientific terms could be to persons who have paid little or no attention to the subject. I never heard that the long name morns multicaulis offered any impediment to the introduc tion of that plant, nor does it, at present, produce any difficulty or ambiguity. Geology proper, however, has but few technical terms, and these are explained in the brief sketch of the science prefixed to this Report ; I know of no other means of obviating the difficulty complained of; when new objects are presented they must have names ; and to bring every thing down to our previous knowledge, would put an end to all progress. It is always pleasant to acknowledge the labors of those who have preceded us, and who have aided in the removal of the difficulties, inseparable from the first steps, in geological investigations.

In the Cabinet of the South Carolina College, an excellent collection of the minerals of the State will be found, which were collected by Mr. Vanuxem in 1826. A list, and an account of the distribution of these minerals, I have appended, taken from Mills' Statistics, where the substance of his report was published* He also published a paper on the Tertiary and Cretaceous formations of the State,t and was the first to notice the Post Pliocene of Charleston. In 1832, Mr. Conrad examined the Tertiary of the Cooper and Santee rivers, and determined the existence of the middle Tertiary, from some fossils discovered by the late Stephen Elliott, Esq. Mr. Lyell has gone over the Eocene of the State, and the results of his observations have appeared in the Journal of the Geological Society of London, and in Silliman's Journal.

Before Mr. Ruffin's Report, there had been but little published in relation to the economic value and extent of the beds of the Tertiary. The existence of the middle Tertiary was barely known, from the inference alluded to, drawn by Mr. Conrad from a few fossils, said to be from "below the junction of the Wateree and Congaree rivers." He pointed out in his Report, localities of this formation, in Darlington and on Goose Creek; and in an appendix to my annual Report, he mentions others on Lynch's Creek, and on Waccamaw river ; so that it * Appendix. t Journal Academy of Natural Sciences, Philadelphia.

PREFACE.

. III is to his labors we are most indebted for an accurate knowledge of this part of the Geology of the State.* Some of the Post Pliocene localities, near Charleston, were discovered by i'rof. L. R. Gibbes* the first list, of any extent, of the fossils of that formation, was prepared by him, and published in Mr. Ruffin s Report. I have also to acknowledge numerous other obligations to the cultivators of science in this State. To Dr. R. W. Gibbes I am indebted for many favors, besides his unabated attention to the best interests of the Survey from its commencement to its close. To Dr. Henry, I owe the opportunity of consulting the numerous rare scientific works in the Library of the South Carolina College. I am under similar obligations to Dr. Ellet, to whose liberality I also owe many useful hints, and much valuable information.

For access, at all times, to his fine collection of recent and fossil shells, and the most liberal use of his Library, containing many valuable and rare conchological works, I am under obligation to Dr. Edmund Ravenel, of Charleston, who alsj liberally communicated to me the result of his observations on the Geology of the State. To Prof. Gibbes, of the Charleston College, my thanks are due, for assistance in comparing recent and fossil shells, but most of all, for preparing for this Report, a synopsis of the Fauna of the State. I have also to acknowledge numerous favors received from Dr. Hume, of the Military Academy. Eor the means of completing the geological section of the State, I am indebted to the politeness of Major Colcock, who placed in my hands a valuable collection of Reports and Field-notes of Rail Road Surveys of the State.

For a fine collection of Post Pliocene fossils, I am indebted to Dr. Burden, of John's Island. From Dr. Barratt, of Abbeville, I received very important assistance in my investigations in Orangeburg, Barnwell and Beaufort Districts, I am also indebted to him for the means of comparing the fossils of the Burrstone with those of Claiborne, Ala. as well as for many other favors. To the highly intelligent Secretary of the Black Oak Agricultural Society, I owe the communication of a fine suit of corals and other fossils from the Eocene of Cooper river. It would be impossible, if it were necessary, for me to separate my own labors from those of F. S. Holmes, Esq. both on the Ashley and in the Post Pliocene of the State. His fine and valuable collection of fossils were placed at my disposal, and I have used it without reserve ; it is chiefly through his labors that the Ashley has already become noted for its organic remains.

Of the kindness and hospitality with which I was everywhere received, which cannot soon be forgotten, and of which it is impossible to think without feelings of gratitude, I can only speak in general terms; for such favors, and for the interest, on all occasions, taken in my pursuits, it only remains for me to return my sincere, heart felt thanks. M. TUOMEY. OF THE GEOLOGICAL MAP. Of the map annexed to this Report, I desire to say one word in explanation. It is obvious, in the nature of the case, that absolute accuracy is not to be expected. For instance, I have taken special pains in noting the trap dykes of the State, yet I am conscious that, in numerous cases, they are not accurately located ; for it often happened that they were observed where there were no points of reference to the map.

In the upper * Perhaps this is not an improper place for me to assume an error into which I led Mr. Ruffin. The external characters of the silicious bed of the Burrstone, together with the existence in it of some polythalamia, derived from the calcareous beds, where they are common, which I took for infusoria, led me to refer it to the infusorial beds ; and it is so stated in Mr. Ruffin 's Report.

PREFACE.

. part of the State, the roads have been so altered, and so many new ones constructed, that there often is but little agreement between them and those on the map. Very many other sources of difficulty could be mention ed, but they will occur to every one, and will serve to explain any discrepancies that may be observed. The geological section is constructed, as far as Columbia and Aiken, from the Rail Road grades published in the report of the President, and the rest of the distance to Saluda Gap from Maj. Colcock's notes. The horizontal and vertical scales are, necessarily, different, and may be ascertained by comparing the distance from Charleston to the Saluda Gap with the height of that mountain. POSTSCRIPT. While the report was passing through the press, A. S. Johnston, Esq. informed me that the Committee on publication had decided that the plates, containing figures of the fossils of the State, which were to have accompanied it, were not essential, and they are, therefore, omitted.

TABLE OF CONTENTS. Frontispiece — View of Table Rock. Page. Map of the Iron Ore and Limestone Region of York and Spartanburg Districts 80 Geological Map of South Carolina (At end of volume.) Preface.

Introduction

.

Chapter I

Objects of Geological Science. — Descriptive Geology.— Practical Geology. — Composition of rocks. — Unstratified rocks. — Granitic and Basaltic rocks. . 1 chapter II. Stratified rocks. — Stratification. — Joints. — Slaty cleavage. — Primary stratified rocks. — Formations. — Systems. — Series and Periods. — Gneiss. — Hornblende slate. — Lime rock. — Mica slate. — Quartz rock — Talcose slate. — Chlorite slate. — Clay slate. — Relation of Igneous and Metamorphic rocks. — Volcanoes and Earthquakes. — Dip. — Strike. — Outcrop. —Metalliferous Veins. — Faults 6 chapter III. Palæontology. — Classification. — Vertebrata. — Mammalia. — Characters of the class. — Orders. — Birds. — Reptilia. — Characters of the class. — Fossil Reptiles. — Orders. — Enaliosauri. — Ichthyosaurus. — Plesiosaurus. — Crocodilia. — Dinosauria. — Lacertilia. — Pterosauria. — Chelonia. — Ophidia. — Batrachia. — Class Pisces. — Sub-kingdom Articulata. — Sub-kingdom Mollusca. — Radiata. — Infusoria. — Fossil Plants _ 18 chapter IV.

Fossilliferous rocks. — Classification. — Palæozoic Series — Lower Silurian. — Upper Silurian. — Old Red. — Carboniferous System — Coal Measures. — Secondary Period. — New Red. — Lias. — Oolite, — Wealden Formation. — Cretaceous System. — Tertiary Period. — Eocene. — Miocene. — Pliocene. — Post Pliocene. Succession of Organic Remains. — Mosaic Account of Creation 40 F TABLE OF CONTENTS. REPORT ON THE GEOLOGY OF SOUTH CAROLINA. chapter i. Page. Granitic Rocks. — Mineral Contents. — Basaltic Rocks. — Trap Dykes and their Distribution. — Flat-woods of Abbeville. — Meadow-woods. — Black-jack lands of Chester. — Mineral contents of the Trap Rocks, 61 chapter II. Stratified Rocks. — Gneiss. — Hornblende Rock. — Mica Slate. — Limestone of the Gneiss. — Limestone of the Mica Slate. — Quartz Rock. — Iron Ores. — Magnetic Ores. — Specular Ores. — Brown Hematite. — Bog Ore - 69

Chapter III

Gold Formation. — Deposit Mines. — Deposits of different ages. — On the Blue Ridge. — Tomassie Valley. — Of Tyger and Little River. — Gold Mines of York. — Fair Forest Mines. — Catawba and Lynch's Creek Mines. — Hale's Mine. — Brewer's Mine. — Smith's Ford Mines. — Mines of Abbeville. — Of Greenville. — Of Pickens 85

Chapter IV

Disintegration and denudation of the Primary and Metamorphic Rocks. — Palæozoic Rocks. — New Red Sandstone 98

Chapter V

Geology of the Upper Districts .Edgefield. — Newberry. — Lexington. — Fairfield. — Kershaw. — Chesterfield. — Abbeville. — Laurens. — Union. — Chester. — Lancaster. — York. — Spartanburg. — Greenville. Anderson and Pickens 104

Chapter VI

Upper Secondary, or Cretaceous, System. — Tertiary Series. — Eocene. — Buhrstone Formation. — Calcareous Beds of the Charleston Basin. — On the Santee. — On Cooper River. — On Ashley. — On Edisto. On the Savannah. — Recapitulation _ 132

Chapter VII

Practical, or Economical, Geology. General views of soils. — Classification of soils. — Physical properties of soils. — Composition of soils. — Composition of Cultivated Plants. — Manures. — Mineral manures. Calcareous manures.— Marls of the State.— Effects of Calcareous Manures.— Rotation of Crops.— Draining.— Soils of the State.— Lime Burning —Metallurgy.— Manufacture of Iron.— Extraction of Gold from its ores.— Of the other Metals found in the State— Building Materials.— Flag Stones.— Fire-proof Materials— Materials for Pottery.— Materials for Mill-stones —Materials for Paints.— Materials for Glass-making.— Materials for whetstones and grindstones— Mineral Springs ___ 212

Appendix

. Fauna of South Carolina Meteorological Tables Vanuxem's Keport Indigo „ xxxui Analysis of Marls from the vicinity of Charleston . ~"~~— — ~ — •» — — — • — — _ — » — »•_ _ — _— _ — _— XXXI V " of Soils of Edisto Island... "" ----- -_..__. ... .... --XX5V111 of the Cotton Lands on the head waters of Cooper River -kjj

INTRODUCTION.

.

Chapter I

Objects of Geological Science. — Descriptive Geology. — Practical Geology. — Composition of rocks. Unstratified rocks. — Granitic and Basaltic rocks. The objects contemplated by the science of Geology may be conveniently distributed under two heads — Descriptive and Practical Geology. Descriptive Geology includes the facts derived from the examination and study of the various appearances presented by the earth's crust, the materials of which it is formed, the manner in which these materials are arranged, whether disposed in erys taline masses, or in beds and strata, the order of succession observed in these beds and strata, the study of the organic remains which they may enclose, and their comparison with the living forms of the present period. It investigates and explains the causes at present in operation, as well as those disturbing forces which have acted in past times — which have resulted in the present form and appearance of the earth's crust.

Practical Geology, on the other hand, has for its objects the application to the ordinary affairs of life, of the knowledge that may have been thus acquired by a careful study of the phenomena exhibited in the earth's structure, and of the general laws which have governed these phenomena. It applies this knowledge to the discovery of substances useful in the arts, such as minerals and ores, and thus it directs the jDractical pursuits of the miner. To the engineer it exhibits the character of the country where his operations may be carried on : and often enables him to anticipate the difficulties to be encountered, arising from geological struc ture; while to both engineer and architect it may render important aid in the selection of proper materials for construction. To the agriculturist it points out the origin and character of soils, and their relations to the rocks from which they are derived ; and in this manner Practical Geology forms, in a great measure, the basis of agricultural science.

DESCRIPTIVE GEOLOGY It is probable that our actual knowledge of the earth's crust extends to a depth of fifteen miles, including the tops of the highest mountains. Sixteen substances, usually considered simple, constitute the greater portion of the materials included in this thickness. Of these, eight are nonmetallic substances : Oxygen, Nitrogen, Sulphur, Fluorine, Hydrogen, Carbon, Chlorine, Phosphorus. Six are metallic bases of the alkalies and earths : Silicium Potassium, Magnesium, Aluminium, Sodium, Calcium. And two are metallic Oxides : Iron, Manganese. Such is the chemical relation existing between these substances, that, with a few exceptions, they rarely occur in nature in their simple and uncombined state. Oxygen, for instance, by its chemical union with the bases of the alkalies and earths, and with Hydrogen and Carbon, produces the well known substances, Silica, Alumina, Potash, Soda, Magnesia, Lime, Water, and Carbonic Acid. — These again, by their combination with each other, give rise to a few minerals, which, by their aggregation, make up by far the greater portion of all rocks.

Thus. Silica alone forms - - - Quartz ; Silica, alumina, potash, or soda, form - Feldspar; Silica, alumina, potash and iron, ----- Mica ; Silica, magnesia and iron, ------ Talc ; Silica, magnesia, lime, alumina and iron, - Hornblende ; Silica, alumina, lime and iron, ----- Argillite; Lime and carbonic acid, ------ Limestone. Numerous other minerals are found embedded in rocks, and entering into their composition ; but of the mass, they generally form but a small proportion, compared with these. The first object of the student of Geology should, of course, be to make himself acquainted with these minerals ; and although it is not easy to give correct ideas of minerals by mere ordinary description, yet these are so widely distributed, so abundant, and so easily recognized, that they offer but little difficulty.

Quartz, which in this State is called white flint, is readily known by its glassy appearance. uneven fracture, and great hardness. It presents a variety of colors, and is esteemed for gems. under the names of amethyst, agate, cornelian, &c. It constitutes nearly one half the mass of all known rocks. Feldspar is distinguished from quartz by its inferior hardness and its distinct cleavage. It has a high lustre, is generally semi-opaque, and is of a white gray or flesh color. It constitutes nearly one-tenth of the earth's crust. Mica is known by the thin elastic plates into which it is readily divided. Its bright shining metallic lustre is a fruitful source of disappointment to unskilful searchers after gold and silver. It is called, in this country, isinglass. Talc is quite soft and greasy to the touch.

From mica, which it sometimes resembles, it is distinguished by the want of elasticity, and by its unctuous touch. It is sometimes known by the name of French chalk : its colors are white and green. Hornblende, in its most common form, presents a confused crystaline structure, and dark °reen color, approaching black. The rocks composed of this mineral are exceedingly tough, and yield with difficulty to the hammer — a fact known to the Aborigines of the country, who used them as the principal material in the construction of their tomahawks and other instruments requiring much strength. Argillite, which is rather a rock than a simple mineral, is well known on account of its exten sive use as common writing slate. It has a fine texture, an earthy fracture, and presents mam shades of color, such as black, grey, red and purple.

Alumina, its principal ingredient, next to silica, is the most widely diffused substance. Limestone is best known in the numerous varieties of marble. It is sometimes crystalized, and is then called calcite, or calc-spar. It is softer than feldspar, and may be readily scratched. It is easily distinguished by the effervescence produced by the application of an acid. It is more abundant in the newer rocks, and constitutes about one-seventh of the rocks of our globe. If attention be now directed to the mineral masses or rocks made up of these simple minerals, and which constitute the earth's crust, so far as man has penetrated, it will be seen that they are disposed in beds or layers, piled up, one upon another, in the manner in which matter would be deposited which was once held in suspension in water ; or else they occur in masses of uniform structure and appearance, and without any traces of those beds or planes that would indicate a mechanical origin.

And thus we have a very natural division of rocks, into two great classes — Stratified and Unstratified rocks. Unstratified Rocks. The examination of this class of rocks will not proceed far before it is seen that it is composed of two groups, varying widely in structure and external appearance. The one consisting of crys taline rocks, in which each of the component minerals presents the appearance of crystalization, independent of the mass. They underlie the stratified rocks, or are pushed up through them, and may, therefore, be regarded as the foundation, or frame-work, of the earth's crust. The rocks composing the other group occupy a less important place, generally only filling the cracks and fissures in other rocks, or spread out over their surface, where they frequently assume regular forms.

These two groups or classes of rocks may be designated as the granitic and the basaltic rocks. Granitic Rocks. Common granite, which is an aggregate of quartz, feldspar and mica, is the type of this class of rocks. It is either coarse or fine, generally depending upon the quantity of the feldspar. Its colors. which are also much influenced by that mineral, are white, gray, or red. Its component minerals appear aggregated promiscuously, and sometimes as if the mica and feldspar were embedded in a quartz base. The ease with which granite splits in two directions, when quarried by a skilful workman, is due to the coincidence of the cleavage planes of the felspar with those of the blocks split out. Fractures or seams of considerable extent, are often seen in granite — not unfrequently dividing it into cubical blocks ; but these are the effects of a different cause.

Granite has various names, derived from the different proportions and mode of aggregation of its constituent minerals : it is called micaceous, feldspathic, or quartzose, as mica, feldspar, or quarts may predominate. Porphyritic granite has the feldspar disseminated through the whole in large crystals, which are often of a different color from the rest of the mass, and hence the striking appearance of some varieties of this rock. Graphic granite is composed of a base of feldspar, traversed by variously shaped plates of quartz. When this rock is fractured in certain directions it presents the appearance of certain alphabetic characters. Albite granite. When felspar contains soda instead of potash it is called albite. When this mineral takes the place of common feldspar in granite, the rock is whiter but less durable than the common variety.

Other minerals, such as hornblende, chlorite, talc, <fcc. often replace the ordinary constituents of granite. Where hornblende takes the place of the mica the rock is called Syenite, and when mica is also present with the hornblende it is called Syenilic granite. Protogine. This term is applied to those varieties of granite in which chlorite, talc, or steatite takes the place of mica. Granite is very widely distributed, being found in all parts of the known world. It rises in enormous masses, forming mountain peaks, and it is also found penetrating other rocks, in the form ol veins. It every where underlies the older stratified rocks, and hence, in common with these, it has received the name Primary, on the supposition that it was the oldest or first formed rock. It is now, however, well understood to belong to various geological periods : for besides forming the great foundation of the earth, it is found piercing and superimposed upon strata of very modern date.

This, however, has nothing to do with the origin of granite — it simply proves that the materials of which it is composed were in a fluid state ; that in this form the mass was erupted or forced up wards through the other rocks, even as late as the commencement of the Tertiary period, where it was consolidated, producing a granite in all respects as characteristic as that found beneath the old est stratified rocks. Granitic veins are also seen to intersect granite. The apparent inconsistency of applying the term primitive or primary to a rock formed at so many and at such recent periods, induced Mr. Lyell to substitute the term Hypogene (formed beneath,) for that name. The term Primary, however, is so well understood, and in such common use, that but little advantage will arise from the change, particularly if we bear in mind the facts just stated.

Basaltic Rocks and Porphyries. These rocks are far more limited in extent than the pieceding ; instead of forming the base or frame-work of the earth's crust, they occur rather in the form of dykes and veins, and appear to have been forced upwards through rents and fissures in the superincumbent rocks. They are, how ever, widely distributed, and sometimes occupy considerable space. Basaltic rocks have been desig nated by the names of whin, trap, greenstone, clinkstone, and amygdaloid. In general, they are more homogeneous in appearance, if we except the embedded minerals which they contain, and rarely present a crystaline structure like granite. Their color is a greyish black, approaching green. A lemarkable difference between these rocks and granite consists in the greater abundance of lime, which is owing to the prevalence of hornblende in all the basaltic rocks.

They occur in veins or dykes in tabular masses, as if spread out over the surface by overflowing. Basalt and trap often occur in beds composed of a series of vertical columns, exhibiting a structure apparently the result of crystaline forces; the sides presented by these columns vary in number from three to nine. This structure is not properly crystaline, but the effect of cooling after fusion, and the consequent contraction, the fractures probably taking the direction of the cleavage planes of some of the constituent minerals. These columns often present a jointed structure, the result of cleavage parallel with the base, which is doubtless due to the same cause. Fingal's Cave and the Giant's Causeway are well known and magnificent examples of columnar basalt. Numerous localities of trap occur in the upper districts of South Carolina.

Greenstone is composed of feldspar and hornblende. It is granular, and sometimes the crystals of its component minerals may be distinguished. The hornblende generally predominates, and im parts its characteristic green color to the mass. Amygdaloid. This name is applied to those varieties of trap or basalt having vesicular cavities filled with kernel shaped minerals. It is probable that the materials composing the minerals found access to these cavities by the percolation of the water holding them in solution. The absence of those silicious minerals which abound in the granitic rocks is a remarkable feature in the rocks of this class. Eurite is, for the most part, composed of compact feldspar : its color is white or grey. It occurs in South Carolina in the form of veins or dykes. Porphyry.