granite, retain their features unaltered; on the northern side, there is interposed, between the latter and the corresponding slates and sandstones of Woodstock, a wide belt of highly crystallized sediments, consisting of fine grained gneisses and quartzites, with micaceous, chloritic and hornblendic schists; while along the axes of the parallel folds into which the slates are thrown, are found considerable bands of other hornblendic rocks, such as diorites and amygdaloids, which at times graduate into true syenites. These crystalline strata are also highly calcareous and at some points contain considerable deposits of limestone, while the slaty and arenaceous beds are almost entirely destitute of this material. It is thus probable that somewhat lower beds are exposed upon the northern than upon the southern side of the granitic axis, but a careful study of both leaves little doubt that, as a whole, they are the same series, while the resemblance of both to the dark argillite series of the southern counties is most striking. Admitting their identity and the resemblance can be traced even to the most minute particulars - we have in this central area, as in that to the south, two essentially distinct slaty groups, of which the dark colored and more or less altered strata last described are one, and the second a series of finer slates, of paler color and highly calcareous, with only scattered scales of mica, occupying much of the country north of the Woodstock Branch Railway. Neither of these two groups has yet been worked out in detail, but from such observations as have been made, it is thought probable that the uppermost group will be found to be continuous with the great area of Upper Silurian rocks known to occupy the northern portion of the county of Carleton, while the lower is an unconformable series, representing some portion of the Lower Silurian formation. In this connection it is interesting to notice that in the northeastern part of the same county, and in a position corresponding to the trend of the beds now described, Mr. Matthew has recently succeeded in recognizing two unconformable series both containing graptolites and other fossils, and which seem to furnish strong corroboration of the conclusions referred to. It may be added that the character of a portion of these fossils, together with the occurrence with the argillites of the upper series of considerable deposits of iron ore, render it probable that they are in part the representatives of the Clinton group of the New York series, while the lower beds, as has been long supposed, are the probable

equivalents of the Quebec group and Taconic rocks of western New England. Should these views be confirmed by further investigation, the general structure of this region will be not unlike that recently described by Principal Dawson in connection with the fossiliferous iron ores of Pictou, Nova Scotia.

GRANITES, ETC.

In this connection it is interesting to notice the peculiar and often very different relations in which the sedimentary beds, which have been described, stand to the granitic and other crystalline rocks with which they are associated. It has already been stated that while, on the southern side of the main granitic axis, the flanking strata even in close proximity to the latter show little evidence of alteration, those upon the north are but little less crystalline than the granite itself; but it may now be added that this difference is accompanied by another which is equally striking, viz., that while along the one the line of contact, where visible, is regulat and uniform, on the other it is characterized by extreme complexity, veins from the granitic mass, of all sizes and shapes and of the most irregular description, penetrating the schistose rocks in all directions, while not unfrequently numerous blocks, or what appear to have been detached masses of gueiss or sandstone, are completely surrounded by or embedded in the granite in such a way as to look like a coarse conglomerate. Notwithstanding this intimate association, however, it is curious to observe that each rock commonly preserves its peculiar features unaltered, the contacts being sharp and abrupt, while the stratification, the texture and even the color of the enclosed masses have been entirely unaffected. While such facts point conclusively to an intrusive or exotic origin for these granitic bands, as well as to the very slight elevation of temperature which must have accompanied their formation, an equally marked but very different mode of occurrence is found to prevail in the case of the dioritic and syenitic rocks which accompany the slates and sandstones farther north. These are equally crystalline, but while containing hornblende in the place of mica, and often large quantities of epidote, they appear to be only a more highly altered form of the associated sedimentary beds, these latter consisting chiefly of bedded ashrocks, felsites, amygdaloids, etc., passing by regular but very

gradual gradations into typical syenites. In neither case is any countenance given to the view that these great bands of crystalline rocks, which traverse the whole breadth of the Province, and extend to the westward through a large part of the State of Maine, are of Laurentian age or of greater antiquity than that of the stratified formations with which they are associated.

UPPER SILURIAN.

Of the Upper Silurian formation, it is only further necessary to say, in the present connection, that, in addition to the areas already referred to, this age can now be definitely assigned to the very remarkable group of rocks surrounding Passamaquoddy Bay, and which include the peculiar orthophyres or felspar-porphyries of Eastport and Pembroke, Me., these latter having been found to rest directly and almost horizontally upon a series of fossiliferous sandstones, identical with those which at the last-named locality have been long known to contain a rich Upper Silurian fauna. Another instance of the difficulty of distinguishing the rocks of this most variable formation is to be found in the occurrence, first observed by Mr. Matthew, of corals and other Silurian organic remains on the Long Reach of the St. John River, in amygdaloidal ash-rocks, which are undistinguishable lithologically from those of the Huronian formation, and which, like those of Passamaquoddy Bay, had previously been referred to this horizon.

Of the later formations of the Devonian, Carboniferous and Triassic, it is sufficient to say that much detailed work has been devoted to each, the results of which are fully set forth in the published reports of the Canadian Survey, but none of these are of such general interest as to require more particular reference here. It is hoped that the geological map, now upon the point of being issued, will awaken renewed interest in the structure of our great eastern geological basin, and lead to its closer correlation with that of the west.

THE CUPRIFEROUS SERIES IN MINNESOTA. By N. H. WINCHell, of Minneapolis, Minn.

THE red shales and sandstones interstratified with the igneous rocks of the cupriferous series along the shore of Lake Superior in Minnesota, show various stages and kinds of metamorphism. While in some places, as at Good Harbor bay, they are not much changed by contact with the igneous layers separating them, in other places they show a broken stratification, and a tough and siliceous texture, as at Tischer's, near Duluth, where these beds are finely and angularly jointed, have a red color and sometimes a jaspery or conchoidal fracture. In other places they take on a dull brown color, passing to a greenish-brown, becoming slaty and firm, or when in close proximity to igneous dikes, becoming black, dense and basaltiform, as at points east of Grand Marais. In the segregation of minerals, the first to appear are calcite and laumontite. These are disseminated with varying abundance through the shaly layers, as well as through the aluminous and red conglomerates, as seen at the mouth of the Manitou river and at numerous other places. They gather in seams, or in certain parts of the mass, or in the form of amygdules throughout the thickness of the exposed layers. This formation of laumontitic amygdaloids is particularly noticeable in those layers whose thickness is from a foot or two to twenty-five or thirty feet, and sometimes several may be seen alternating in the same bluff, or in a few rods along the shore, with beds of undoubted doleritic rock, as on the west coast of Agate bay, where may be seen five layers of igneous rock with four alternating layers of crumbling, thin-bedded laumontitic amygdaloid, styled "volcanic grits" by Norwood.

These amygdaloids are very susceptible to the destroying action of the waves and of the atmosphere, and their disintegration is the immediate cause of many of the purgatories and isolated arched beds of traprock that ornament the north shore of lake Superior.

When the source and supply of the heat were more continuous, involving greater thicknesses of the sedimentary beds, the siliceous material was more thoroughly fused and disseminated among the other elements. The more limited supply of air and water at

these greater depths seems to have produced, at least is coincident with, a greater abundance of felspathic material, instead of calcite and the hydrous zeolites, throughout the sedimentary layers. Thus the whole is sometimes changed to a non-differentiated ferruginous felsite. When the process was carried a little farther, crystals of red orthoclase appear in the mass, or of orthoclase in the form of translucent adularia, as in the rock of the "great palisades." When the metamorphism is carried still farther, involving in its slower progress large thicknesses of the red sedimentary shales and sandstones, they become almost wholly crystalline, as seen in the red bluff that incloses Beaver bay on the west, and in the red granite bluff a few miles east of Beaver bay. The relationships of these changes with one another, and to the igneous rock, are evident at numerous places along the shore between Duluth and Grand Portage, and on Isle Royale; and their significance and application to the stratigraphic gcology of the northeastern part of the state are very important. On passing inland from the lake shore back of Grand Marais, and up the Devil's Track and Brulé rivers, the red semi-metamorphic slates of the shore can be followed over a wide extent of territory, gradually becoming more changed and crystalline, in receding from the lake shore. They pass into red granite and gneiss (hornblendie) which rises in conspicuous hills, and shows perpendicular exposures along the lakes and streams, sometimes several hundred feet high, as at Brulé mountain, and at Misquah lake (T. 64.1 W., Sec. 32). In some places this highly crystalline condition of this red formation is seen to give place suddenly to areas of igneous rock of a dark color, and showing a very different mineral composition, and then to return again. This takes place sometimes on the high hills, the two kinds of rock alternating superficially in irregular patches, as at Duluth, and at Duck lake and Frog Rock river on the portage trail from Little Saganaga lake to the head waters of the Temperance river, in the northeastern corner of the state. Sometimes the tilted red sedimentary beds seem to be overlain by the igneous rock and sometimes underlain by it, the red rock, when consisting of sandstone at first, having been hardened into a quartzite. Several tilted red quartzite hills, very similar to the quartzite hills at New Ulm, and in Cottonwood and Rock counties, occur in this connection at