The geology of New Hampshire. A report comprising the results of explorations ordered

Preface

Nearly two years and a half have been occupied in the compilation and printing of this volume. Material additions to our knowledge of the rocks, consisting of two summers' field-work, have often corrected, improved, and added to the statements already printed. This has been the most marked in the White Mountain district. Mr. Huntington has performed an excellent work, in his chapter upon the Coos and western Merrimack districts, particularly in distinguishing the coarse granite belt and the fine-grained division of the Bethlehem gneiss, the first being of practical consequence in determining the best places to work mica quarries. We have constantly endeavored to state all facts in the briefest possible language ; and, in consequence of the immense number of observations recorded, the last four chapters have been much abbreviated. In spite of all our efforts, the subjects of Surface Geology, Economics, Mineralogy, and Lithology are crowded out into a third volume, nearly a hundred pages of which are already printed. Mr. Warren Upham has undertaken the description of the Modified Drift ; and Mr. Geo. W. Hawes will discuss Mineralogy and Lithology. Both these treatises will be of rare value. We have undertaken the collection of several sets of specimens illustrating our Lithology, each consisting of two hundred and fifty varieties. These may be found at the college museum, at the state house, and at the normal school. Other sets are on hand for exchange or sale.

The study of the topography of the state has not ceased with the publication of Part I. Our labors have been unexpectedly successful, so that we shall present upon the geological map contour lines for every hundred feet throughout the state. These lines will not interfere with the coloring representing the distribution of the formations, but will the rather aid in understanding their relations to mountains, plains, and valleys. We have also

151497

IV PREFACE.

constructed a model of the state, about fifteen feet in length, on the scale of one mile to the inch horizontally, and one thousand feet to the inch vertically. Copies of this model are to be found at Concord and Hanover. It is our belief that this topographical model is one of the most important practical results of the survey. Special attention is called to the unique method of arranging rocks, in relation to geography and structural geology, described in Chapter IX.

Arrangements have been made for the publication of our geological map, upon the scale of two and a half inches to the mile, in the best style, by Julius Bien, of New York. The engraving is completed, and it only remains to execute the coloring. We had hoped the sheets might be ready for distribution with this volume. Most of the descriptions refer to the map, so that they cannot be thoroughly understood without it.

C. H. HITCHCOCK.

Hanover, May 12, 1877.

Table Of Contents

Chapter. Page.

I. THE RELATIONS OF THE GEOLOGY OF NEW HAMPSHIRE TO THAT OF THE ADJACENT TERRITORY, By C. H. Hitchcock, 3

II. GEOLOGY OF THE COOS AND ESSEX TOPOGRAPHICAL DIS- TRICT.

Chapter I

THE RELATIONS OF THE GEOLOGY OF NEW HAMPSHIRE TO THAT OF THE ADJACENT TERRITORY.

^EFORE discussing the particulars of the geology of New Hampshire, it will be desirable to recall the general features of the geological structure of the continent, in order to properly understand our place upon it. Next, we shall turn our attention to the physical characteristics of that particular section of which we find ourselves an important component; and then examine more minutely the various groups of strata peculiar to our district. It will be to the latter topic that we shall devote the most attention.

Continental Subdivisions.

North America is rudely triangular in shape, with its most prominent mountain ranges adjacent to the eastern and western borders, the latter being the broadest, highest, and opposite the larger ocean. The rocks, so far as needful for our present purpose, may be classified as the crystalline, two sets of sedimentary sandstones, limestones, and shales, and, lastly, the loosely-coherent superficial formations occupying various basins and water margins underlaid by the more compact ledges. These four groups correspond in order with the Eozoic, Paleozoic, Mesozoic, and Cenozoic systems of geological authors, the first being the oldest, or that first reclaimed from the universal ocean.

In order to illustrate the relative positions of these four classes of rocks, and the consequent method in which the continent has been gradually built up, I have prepared a small geological map, which will exhibit these mutual relations far better than words. The projection is the ordinary one, exhibiting the surface as nearly as possible like nature, and not distorting the northern regions so fearfully as Mercator's. The formations for the United States are copied in outUne from the geological map by W. P. Blake and myself, published in the supplementary atlas pertaining to the ninth census, Gen. F. A. Walker, superintendent. The delineation of the northern portion is taken mainly from a map by Robert Bell, in Walling s topographical atlas of the dominion of Canada, and from notes respecting Alaska, kindly furnished me some years since for another purpose by W. H. Dall. As the scale is so small, the absence of many considerable outcrops, especially in the Rocky Mountain region, is a matter of necessity.

An inspection of our map will show a natural division into the following grand districts, the most important being stated first, without regard to age: i. The immense Rocky Mountain crystalline area, extending from Alaska into Mexico. This is the foundation for innumerable minor basins, which cannot be represented. 2. An equally extensive crystalline area, embracing the north-eastern section of the continent, chiefly in the territories of Canada, Labrador, and Greenland. This portion is rather quadrangular in shape, with a central depression for the Hudson's Bay Paleozoic area. 3. The interior Paleozoic basin, nearly divided along th^ middle so as to separate between the arctic and eastern United States regions. 4. A somewhat similar Mesozoic region lying to the west of the preceding, and broadest southerly. 5. The elevated fresh-water Tertiaries of the upper Missouri, and the marginal Cenozoic groups on the Atlantic, Gulf of Mexico, and the northern waters off Alaska. 6. The Atlantic belt of Eozoic formations. 7. Various local basins, as the Paleozoic of Acadia and of the Colorado river; the Mesozoic of Vancouver's island, California coast range, of Utah and New Mexico, and of Alabama and Mississippi; Cenozoic of Rocky Mountains, Greenland, etc. It is the sixth of these districts that we shall call particular attention to very soon.

I cannot resist calling attention to a very few points suggested by this map : First, At the close of the Eozoic period the grand features

GEOLOGICAL RELATIONS.

of the North American continent were distinctly outlined, including the Atlantic and Rocky Mountain areas. The work of later geological periods seems to have been the filling up the bays and sounds between the ai ijM ^p^^H^^atj''j

I. MeatcAt

^^^^SK Fig.

xp^ ixv

V

XoKslt^Ae tr.lJVi'onv <Ji-ee>vw\«1 great islands, elevating the consolidated mass into a continental area, and probably submerging other equally important islands beneath the Atlantic and Pacific oceans.

Second. Although the Rocky Mountain Eozoic area existed very early, it seems to have oscillated considerably during the Paleozoic and Mesozoic periods, sometimes elevated and often submerged, while the Eozoic districts of the east remained elevated above the sea from the very first. This is shown partly by the gradual extension westwards of the submarine deposits. East of the Mississippi river there is scarcely anything in the interior basin later than the coal measures. Then comes the development of enormous Triassic and Cretaceous deposits between the long Paleozoic strip from Texas to the Arctic zone and the Rocky Mountains, while along the latter region we fail to find the former groups to any very marked extent, as would be expected were the western outcrops steadfastly elevated at the same period with the eastern. If we may say that the North America of Triassic times extended from Greenland and the Atlantic ocean to Texas, we may also say that, by the close of the Mesozoic, she had annexed to herself, by means of a specially constructed causeway, the whole of the Rocky Mountain series of islands. Possibly the genius of the continent is now looking forward to a similar absorption of the West India islands, through the filling up of the straits of Florida and the intra-insular spaces.

Third, There were two promontories extending south-easterly from the early continent, — one the well-known Adirondack area, and the other the metalliferous district near Lake Superior. The latter sent off a prominent spur also towards the Laramie Mountains of Wyoming, projecting eastwardly from the Rocky range. In fact, it is not unlikely that a bridge connected these projections of land through the Black Hills during middle Paleozoic times.

Fourth, The immense areas and the enormous thicknesses attained by the Eozoic formations, especially in comparison with the later groups, suggest that the earlier rocks have yet revealed to us very little of their history. The later formations occur in comparatively thin incrustations, easily studied and identified through fossils. The earlier groups are much more difficult of identification, are best developed in the thinly settled or absolutely wild districts, and hence have not yet assumed that importance in stratigraphical columns which they are destined to receive in the future. We trust, therefore, that geologists will not be too hasty in deciding against the attempts of this volume to set forth the reality of several new subdivisions in the Eozoic column of the Atlantic system.

The Atlantic Area.

In the chapter upon Topography, vol. i, p. 170, mention is made of two sections of the mountains along the Atlantic, the first culminating in western North Carolina, the second in New Hampshire. By referring to Fig. I, I think it will appear that the Atlantic system should be extended to include the Eozoic area of Newfoundland, though separated by the Gulf St Lawrence. The lowest line between the northern and southern sections reaches tide-water along Hudson river; and as the disappearance of the Cenozoic margin at Cape Cod suggests a more extensive depression of the land northerly, it is not strange that the remotest section of the Atlantic area should be depressed more than the others. There is a correspondence in the arrangement of the Newfoundland formations with those of the adjacent provinces of New Brunswick and Nova Scotia. The Paleozoic rocks of the north-west side of Newfoundland correspond with those of Gasp6 ; the central gneissic area is continuous from New Brunswick; and, not to mention all, the outer Eozoic area of the outer Newfoundland island is the continuation of the Nova Scotia Atlantic strata. Hence I believe a new classification is possible, — that of the northern or Newfoundland, the middle or New Hampshire, and the southern or North Carolina sections of the Atlantic range. The middle and southern will correspond with the northern and southern sections of the Appalachian system, so ably set forth by Prof. Arnold Guyot, in his memoir published in the American Journal of Science and Arts, H, vol. xxxi, p. 157. The Appalachian system relates more properly to the Paleozoic elevations to the west of the Atlantic chain, the name having been improperly extended in application through false theories of the age of the New England rocks.

In the southern section Laurentian areas are abundant. They are less so in the middle district ; but I will now introduce a map and sections, which will characterize the formations with considerable minuteness.

The Map.

Herewith is annexed [Plate i] a small geological map of New England, with portions of the adjacent states and provinces. The territory includes what might be termed the "Champlain island," or that portion of the continent east of the Hudson valley which existed as an isolated district for a long time after the Glacial period, the then submerged Hudson, Champlain, and St. Lawrence valleys, and the remoter portions of Nova Scotia, Cape Breton, and Newfoundland. It corresponds exactly with the middle and northern section of the Atlantic belt, as defined above. The lines were carefully drawn upon the scale of twenty-four miles to the

8 STRATIGRAPIIICAL GEOLOGY.

inch, and theii reduced to about one hundred miles to the inch by pho^ tography. The area has been sufficiently extended to include all the Canadian representations of the Labrador system. Outside of New England, the geological boundaries have been copied from Logan's map of 1869, as amended by Dawson's sketch of Nova Scotia and Prince Edwards island, Prof. L. W. Bailey's and G. F. Matthews's report upon New Brunswick, and Alexander Murray's recent map of Newfoundland. The authorities for New England are my own maps and observations in the four northern states, my father's map of Massachusetts of 1844^ Percival's Connecticut, Jackson's Rhode Island, and a few isolated facts presented by various authors. It is the first published attempt -to subdivide the crystalline and metamorphic formations of all this region.

Looking at the map in the most general way, a fourfold division naturally suggests itself. First, the more ancient gneisses and granites, embracing the Laurentian, Atlantic, and Labrador systems. Second^ the immense areas of hydro-micaceous and micaceous schists, which are here termed Huronian. Third, an equally great expanse of clay slates and all the known fossiliferous groups of the Paleozoic. Fourth, the comparatively restricted patches of slightly inclined areas of Mesozoic and Cenozoic age. All these divisions possess characteristics peculiar to New England, those of the first two being the ones most important to u^ in the discussion of the geology of New Hampshire.

The first division is divided into four parts, — first and oldest, the Laurentian; second, the Porphyritic gneiss and various undetermined granites ; third, the Atlantic; and fourth, the Labradorian, The second division cannot yet be well subdivided upon the map. The third consists more largely of clay slates than anything else in the East, with all the well determined Paleozoic formations of New York and Canada. These slates are grouped under the general term of Silurian and Cambrian of the Atlantic area, in distinction from the same formation in the St Lawretice and Champlain valleys^ These might be further divided, did the scale of the map allow minuter representation. The outcrops of the Devonian and Carboniferous are also distinguished frdm the preceding. The fourth portion is easily divided into Triassic, Cretaceous, and the capes and islands off southern New England, composed of Tertiary and Alluvium.

K ELIOT yPE

Laurentian, Beginning at the south-west corner, we observe three areas marked as of this age. The greater one comprises the highlands of New York and New Jersey. Nearly all writers have agreed in this reference, save that Prof. H. D. Rogers at one time regarded the crystalline limestones of New Jersey as metamorphosed Lower Silurian. Prof. W. W. Mather separated from this "Primary" area various metamorphic limestones and schists, thought to be of Silurian age, which are mostly placed with the Atlantic system upon our map. Hall and Logan, in 1864, found this so-called primary area in eastern New York to be the same with what they had elsewhere called Laurentian.* Prof. Dana comes to a similar conclusion.!

The two smaller areas to the north-east, partly in Connecticut and Massachusetts, are Formations K 2 and K 3 of Percival, and are accepted as Laurentian by Profs. Hall and Dana. The correctness of the bounds of the latter area in Massachusetts may be open to question.

The large areas of Laurentian, in the Adirondacks and north of the St Lawrence river in Canada, are the exposures originally called by this appellation by Sir W. E. Logan.

In New Brunswick this formation has been outlined in accordance with the views of Bailey and Matthews.

In Nova Scotia, the metamorphic rocks accompanying the magnetic iron ores of the Cobequid mountains and an extensive area running the whole length of the peninsula, are referred to this period by Hugh Fletcher, of the geological survey of Canada, in the topographical atlas of the Dominion of Canada (1875), pubHshed with the approval of Mn Selwyn, the director of the survey. In accordance with the views of T. Sterry Hunt, the latter area is placed in the Atlantic group.

The more central portions of Newfoundland, embracing more than half its territory, may be referred to the Laurentian.

Porphyritic gneiss and undetermined granites. The importance of this group in New Hampshire has been set forth to some extent in the first volume. Upon the authority of the text of the Massachusetts report^ I have added an area between Worcester and the Connecticut valley. There is probably another in Warwick. I cannot satisfy myself from Percival's report that this formation occurs in Connecticut. The one

* Amer. your. Set., II, vol. xxxix, p. 96. f Id. Ill, vol. iii, p. 255. VOL. II. 2 thus named by him near Bridgeport is lithologically unlike the New Hampshire rock, resembling, however, a portion of our Bethlehem group. In Maine, there is a small area midway between Rangeley lake and the Kennebec river in the west, and along the Penobscot river at the granite quarries. An unusually broad band of it lies between Bangor and' Ellsworth, represented in one of the long sections in this chapter. The other areas are mainly of the undetermined granites. The largest is connected with the porphyritic granite just mentioned, and it reaches from the islands of Penobscot bay, or possibly St. George, to the Bay of Chaleur on the Gulf St. Lawrence, a distance of 290 miles, and a width of from two to twenty-two miles. That near New Bedford, Mass., is along the same general line of outcrop. It is everywhere flanked by the Huronian. In the neighborhood are the similar areas of eastern Hancock and western Washington counties. Me., and the one extending from Addison, Me., nearly to the St. John's river. A portion of this latter area is called Laurentian by Bailey and Matthews in the New Brunswick report, and they are all referred to this horizon in the topographical atlas of Canada. Another important granitic area is that of Mt. Katahdin. Much of it is surely not porphyritic, and is not unlike certain Labrador granites. As all these granites are quite ancient, they are associated together in the representation of their geographical positions, though not necessarily identical in age.

Atlantic System, This system commences at New York city, and extends north-easterly through Connecticut, thence more northerly through Massachusetts and Vermont, along the Green Mountain range into Canada. Probably the Montalban and Lake groups are both represented, especially in western Connecticut. The Green Mountain range has some relation with the Montalban. The eastern Connecticut range branches first to New Bedford, second to near Newburyport, third to Manchester, N. H., and fourthly along the western part of New Hampshire continuously to the White Mountains^ and thence as far as the Androscoggin lakes in Maine. From these lakes the presence of this rock is general west of the Androscoggin river, west of the Kennebec and Penobscot rivers, also below Augusta and Bucksport. . Small areas exist at the head waters of Dead river in Franklin county, in New Brunswick, and Nova Scotia. The areas of this system in Newfoundland are not yet

GEOLOGICAL RELATIONS. II

known with precision ; but it is likely that future investigations will add to their present representation upon the map, at the expense of the Laurentian.

Labrador System, All the known Labrador areas in eastern America appear on this map. Five of them lie north of the River St. Lawrence. One of the largest is situated a few miles north-west of Montreal, much of it evidently concealed by the Lower Silurian groups. Next is a small area bordering the St. Lawrence, on the Montmorency river, above the falls. Its northern extremity is not over fifteen miles from the Murray Bay area. A fourth is on the Saguenay river, below and east of Lake St. John. The fifth is on the Moisie river, well towards Labrador. Still another mass of labradorites has been recently reported in the south-west part of Newfoundland. The Adirondack area is given as carefully as possible from Emmons's descriptions of his hypersthene rock. All these terranes are accepted as types of the Labrador system outside of New England.

After the discovery of the physical structure of the granites and labradorites of Pemigewasset, it occurred to me that several granitic districts in Vermont might perhaps be included with it, and they are so delineated on the map. They are in the northern part of Essex county, about Willoughby lake, Craftsbury, and the high lands east of Montpelier. It may be that Megantic mountain, Canada, belongs to the same system. There are good reasons for believing that granitic rocks of perhaps Silurian age have penetrated the earlier Labrador outflows in Vermont. Besides the Pemigewasset and Starr King mountain areas, I have marked in the same way the eruptive rocks of Red hill in Sandwich, Ossipee mountains east of Winnipiseogee lake, and Gunstock. In Maine, the granite of Biddeford closely resembles the Conway division of New Hampshire, while that of Kennebunk is related to it. The Sanf ord area carries f elsite ; while the York division is like the sienite of Exeter, Dover, N. H., Gloucester, and Quincy in Massachusetts.

Huronian, The rocks referred to the Huronian cover immense areas. A very important one, and the most characteristic of all, is that referred to the Quebec group by Sir W. E. Logan. Beginning at Granville, Mass., it passes into Vermont and Canada east of the Green Mountains, connecting not far from the province line with the wider belt starting at

Ripton, Vt The two united continue to the end of the peninsula of Gasp6, passing the city of Quebec, and adjoining the St. Lawrence beyond this point. An interesting spur from this area extends from Memphremagog lake to Weedon, P. Q. The next area is the one occurring along Connecticut river, commencing at Rockingham, Vt, expanding to the Ammonoosuc gold field, winding along the Upper Ammonoosuc in Stark, Milan, Dummer, Whitefield, and Dixville, to connect with a broader expanse in Pittsburg, the corner of Maine, and so on along the Quebec and Maine boundary to the head waters of the St. John's river, thence near the Maine line almost to the St. Francis river, separating the most northern angle of Maine from Quebec and New Brunswick. There is a small attendant of this terrane near Moosehead lake, Me., while the felsite of Mt. Kineo is doubtfully referred here, also.

The next area in size extends from the Bay of Chaleur past the Kennebec river in Maine, enveloping the long granite ridge of nearly 300 miles' length, mentioned above. Smaller outcrops exist along Dead river, north-easterly from the Katahdin granite, at the mouth of the Penobscot river, three or four in New Brunswick ; and the Portland rocks, possibly including the Merrimack group in Massachusetts, some feldspathic rocks about Boston, and possibly those associated with serpentine and dolomite at Newport, R. I., belong here. The small area west of New Haven, Conn., is evidently a part of the Connecticut River range, the intermediate portions being largely covered by the New Red Sandstone.

In Newfoundland the Huronian system occupies chiefly the south-eastern promontories. The reference of these rocks to the Huronian is the more satisfactory, since it is at the instance of Alexander Murray, Provincial geologist, who was one of the first to describe this system in its typical locality upon Lake Huron. It may be that portions of the strata thus referred by him, called the "Intermediate series," will prove to be higher in the scale, more especially since they yield an Arenicolites and Aspidella,

Several areas of andalusite and mica schists in New Hampshire are left unrepresented upon the map, though indicated by lettering. At the moment of writing, it is not clear to which of the great subdivisions these rocks should be referred. Mts. Monadnock and Kearsarge are composed of this formation.

Cambrian and Silurian, It is in the Cambrian and Silurian formations that the New England rocks show very distinctive peculiarities, and I have therefore distinguished between them upon the map. In the St. Lawrence, Champlain, and Hudson valley we have the following series :

In the St. Lawrence valley the bottom member is the Lower Potsdam group. Skirting the west base of the Hoosac and Green Mountains, this is a quartzite i lOO feet thick. Near its termination in northern Vermont there succeeds a mixture of red sandstone and mottled sandy dolomites, about 300 feet thick. In New York and northern Vermont two areas of clay slate occur, with a thickness of at least 3000 feet. In Quebec the older slate, with interstratified thin limestones, belongs to this series, the quartzite and sandstone not appearing. There are limestones of this age at Belle Isle, Anse Au Loup, and Bonne bay. This group is characterized by the presence of Olenellus,

The Upper Potsdam is almost uniformly a sandstone, with fossils indicating its existence as an ancient sea-beach. Its surface is covered by ripple marks and crustacean tracks. The thickness along the Champlain valley is about 250 feet; north of the Adirondacks it rises to 300 and 700 feet. About 75 miles below Quebec a large area of related rocks has been described by Richardson, having a thickness of 2000 feet. At the remotest localities named above, the thickness of both the Potsdam periods rises to 11 74 and 2020 feet. At Canada bay the mass is 5600 feet thick, according to Murray.

The calciferous sandrock is about 300 feet thick in the Champlain and St. Lawrence valleys. It crops out occasionally on either shore, and is developed in Newfoundland. It is overlaid by over 1000 feet of limestones containing a peculiar set of fossils, referred by Logan and Billings to the Upper Calciferous, a formation entirely absent on the main land.

Next comes an immense thickness of slaty and calcareous rocks, intercalated in the geological column quite recently, and known as the Quebec group. Much remains to be learned respecting its limits, but it may embrace most of the limestones, marbles, and talcoid schists of western Massachusetts and Vermont, amounting to 4000 feet or more. They somewhat exceed this thickness adjacent to the province line, in Highgate, Vt., and Phillipsburgh, P. Q. Logan describes similar rocks near Quebec, with related fossils. He has associated with them, upon theoretical grounds, the whole of the Huronian series from southern Massachusetts to Gaspe, dividing it into the Levis, Lauzon, and Sillery formations. He supposes the latter assemblage has been metamorphosed so as to lose its original mineralogical character. The two sets of beds may often be distinguished by the presence or absence of fossils, the Huronian being usually destitute of any decided evidences of life. The Quebec rocks are associated with the preceding group, also, in northern Newfoundland, attaining a thickness of 6600 feet.

Next in order are the Chazy, La Motte or Black River, and Birdseye limestones, not usually much over 150 feet thick, and, so far as known, confined to the Champlain and Upper St. Lawrence valleys.

The Trenton limestone is one of the most characteristic of the Lower Silurian formations. In Quebec and New York the maximum thickness is 600 feet. It may be represented by the lower limestones of Anticosti island; at least, more than 1200 feet thickness is referred to the Trenton and Lorraine series combined.

The Utica slate is rather a local deposit, estimated at 300 feet along the Champlain and St. Lawrence valleys. It passes into the Lorraine shales, or Hudson River group, which everywhere accompanies the Utica formation. Logan says it must be 2000 feet thick in Canada. These shales in New York are the equivalents of limestones in Ohio, etc., just as seems to be the case in Quebec and Anticosti.

Two interesting conclusions may be derived from this summary of the Cambrian and Silurian of the St. Lawrence valley: first, the thickness uniformly increases in passing north-easterly ; secondly, slaty, sandy, and siliceous rocks occasionally change into limestones. Both these features are explicable upon the theory of the deepening of the ancient ocean north-easterly, the slates increasing in deeper water, and the sea-beaches corresponding to calcareous accumulations out at sea.

The Upper Silurian groups are sparingly represented in the St. Lawrence valley. There is nothing of this age west of Montreal, in the area of the map. St. Helen's island, in the river opposite Montreal, belongs to the Lower Helderberg. Farther east are considerable masses of red shale, occupying at least three outliers, which are referred by Logan to the Medina period. Near the end of the Gasp6 peninsula are 2000 feet of limestones, apparently a great development of the Lower Helderberg.

PLATE II.

The upper members of Anticosti island, amounting to more than looo feet, appear to range through the whole of the Upper Silurian. The principal development of the Upper Silurian is therefore in the neighborhood of the St Lawrence gulf, in the same district with deep sea deposits of the preceding system. They may connect with the north-eastern extension of the more eastern ranges of the same age.

Let us now note the character of the Cambrian and Silurian formations of the eastern or Atlantic. We find, first, a series of slates rather older than the Lower Potsdam, characterized by the presence of Paradoxides, At Braintree, Mass., are clay slates of this age several hundred feet thick, associated with great thicknesses of grits and conglomerates, shown upon Section i of this chapter. Related rocks are abundant along the New Hampshire and Maine coasts. Near St. John, N. B., they have been studied carefully, and consist of slates and grits certainly 2000 feet in thickness, with the fossils Conocoryphe, AgnosttcSy EllipsocephahiSy Microdiscus, and Paradoxides, In south-east Newfoundland the last of these genera has also been found; also, 6000 feet of the Lower Potsdam or Olenellus formation. In Nova Scotia the auriferous rocks are latterly referred to the Potsdam series, or the Lingula flags of Great Britain. Their thickness is very great, probably exceeding that of the Potsdam rocks below Quebec, in the St. Lawrence valley.