Alpena County, Michigan - Topographical and Geological Character of the County, 1903

And Vicinity

Alpena county is bounded on the north by Presque Isle county, east by Thunder Bay, south by Alcona county, and on the west by Montmorency county, which, at present - 1876 - is attached to Alpena county for judicial purposes. It includes townships 29, 30, 31 and 32 north, of ranges 5, 6, 7, 8, 9 and 10 east, taking in all of Thunder Bay and the islands. It has an area of about one thousand four hundred and forty square miles. It contains approximately three hundred ninety-one thousand six hundred eighty acres of land. The surface descends a little to the south and east, and is from gently rolling to rolling. The timber is of great variety, and is no indication of the soil on which it grows. Sometimes a rich argillo-calcareous loam is covered with white and black birch, aspen, balsam, tamarack, cedar and a few small sugar, hemlock, and norway and white pine. The principal timber is pine, hemlock, sugar, beech, cedar, balsam, white and black birch, black ash, elm lynn, poplar, spruce, etc. The soil is mostly a rich loam, reposing on limestone rock, and containing all the elements necessary to make the agricultural capabilities of Alpena county compare favorably with any county in the State. A few spots of arenaceous soil is met with, but it contains large quantities of carbonate of lime and magnesia. It also contains considerable ammonia, and it onl}' requires a little addition of vegetable matter, and a sprinkling of salt, to make it very productive, so long as the ground does not suflPer for want of rain. The salt produces chemical action in the soil, and dissolves the silica. On this kind of land, the seed should be put in with a drill or hoe, so that it will be covered the proper depth, and the land prepared by a roller, so

Thunder Bay river enters Thunder Bay on the southwest quarter of section 23, in township 31 north, of range 8 east, and is the principal stream in the county. The river, with its branches and their tributaries, take their rise in, or run through, the counties of Montmorency, Oscoda, Alcona, Presque Isle and Alpena, and drains and affords log-running facilities for thirty-nine townships. The river is 197 feet T.-ide where it divides the city, on First street, but is much wider between this point and the mill dam. With nine feet of water on the bar, and fourteen inside, it is navigable only three-fourths of a mile. The river, from its mouth to the Broadwell rapids, by its serpentine course, is about five miles; and the river rises thirteen feet. It is from four to six rods wide. Near the section line between 15 and 22, the river passes over a limestone ledge, now covered by water of the dam, nine feet four inches, which the writer believes to be identical with the limestone found at Sunken Lake. From the foot of the rapids to Trowbridge's dam is 231 chains, by the river, and the fall of the water from the summit level of the Trowbridge pond to the foot of the rapids is sixty-five feet; and the river is from eight to twenty rods wide. At the time the writer made the survey, he noticed at one place an exceptional dip in the rock, a short distance above the Broadwell pond, where the dip of the rock was east, but was only three and one-half feet in forty rods. The Trowbridge dam slacks the water up the river a short distance above the North Branch, and the perpendicular fall of water from this point to the bay is seventy-eight feet. From the level of the Trowbridge pond to the head of Long Rapids, the rise can not be less than seventy -eight feet more. The river is rapid above this place, and runs over limestone ledges, in town 31 north, of range 4 east, town 30 north, of range 3 east, and has a rise of not less than fifty feet more, making a total fall of water from

Devil river is a small stream, taking its rise in a small lake near Thunder Bay river, and runs south through Mud Lake, and empties into Thunder Bay, twelve miles south of Alpena. It has a log-running capacity for about six miles.

Long Lake is a beautiful sheet of inland water, being in Alpena and Presque Isle counties. It is eight miles long and from one to one and a half miles wide, surrounded by good farming lands, densely covered with hardwood. The waters are well stocked with fish, the principal being pike, bass and sunfish. The outlet of Long Lake, called by the writer "Crystal river," from the clear, crystal appearance of the water, is a large stream in the spring, and dwindles to a small brook in the summer. It runs nearly east from the outlet to Lake Huron, and on its way passes through two small lakes, mostly surrounded by high bluffs of limestone. In one of these lakes is a subterranean passage for the water, of sufficient size to pass nearly the entire stream during the lowest stages of water in the summer.

The city of Alpena is located at the mouth of Thunder Bay" river, which enters Thunder Bay near its head, in forty-fifth degree of north latitude, and eighty-three degrees and fifty minutes west longitude, in sections 22, 23 and 27, in town 31 north, of range 8 east, and is the county seat of Alpena county. It is, by section line, twenty miles west and one hundred and ninety-two miles north of Detroit, and twenty miles east and ninety-six miles north of Bay City. It is north from Ossineke twelve miles, and west from Thunder Bay Island twelve miles, and south from Presque Isle harbor about eighteen miles. At the time the writer first visited the place now occupied by the city of Alpena, there was, on the east side of the river near the foot of Dock street, a narrow ridge of land et- teuding east, aloDg the bay shore, for about eighty rods. Near the river, aud extending to the bay, was a beautiful oak grove, containing about four acres, where the Indians camped, feasted, drank their "fire soup," sang their war songs, danced their war, religious and festive dances, held their councils, and buried their dead and feasted their spirits. North of this, and near the river, was a narrow ridge, crossed by a small stream, on its way to Thunder Bay river, and covered with a thicket of white birch, aspen, cedar, and a sprinkling of norway and white pine, and east of this was a dense cedar and tamarack swamp. This ridge widened as it extended north, until it reached the vicinity of Walnut street, where it was about forty rods wide, and covered with a belt of large timber, of hemlock and pine. It thence extended north, into open norway pine plains. On this ridge was a deep-worn Indian trail, from the mouth of the river to the then rapids, near the section line between sections 15 and 22, in town 31 north, of range 8 east, and now covered by the mill pond, where the Indians fished for sturgeon, pike, pickerel and suckers, which were in abundance, and sometimes whitefish. From this point were two trails, one extending north, throuirh section 16, to Long Lake, and the other extending up the river. On the west side of the river, also, was a small ridge. A line, commencing near the foot of Second street, and thence running to the corner of Chisholra street and Washington avenue, and from thence reaching the bay a little below Messrs. Campbell & Potter's dock, would separate the ridge from the swamp. All of that portion east and south of this line, and reaching to the bay, was a sandy ridge, covered with small pine, white birch and yellow oak; and all west of this line, for a mile or more, was a dense tamarack and cedar swamp, filled with water, and well stocked with batrachians, whose loud prate gave token of approaching spring. By the united efforts of thousands, the timber has been removed, the swamp drained of its water, and the croakers, like the smoke of the Indian's wig-wam, are growing less every year, and soon will be known as only a something of the past. This swamp, so abhorrent a few years ago, has become valuable property, on which, in 1876, is standing beautiful residences, the abode of intelligence, peace and plenty. From Second street, north a few rods, was a small brook, winding its way to the river, and bounded by a cedar swamp about fifteen rods wide. North of this swamp was a piece of high land, containing about thirty acres, which was well timbered with white pine and hemlock. This ridge narrowed to a strip near the river, and extending north to the norway and spruce pine plains. On this ridge, also, was a deep and well marked Indian trail, which had been tramped by moccasined feet for many centuries. It led to the rapids, before mentioned, and thence to the big bend of the river, near Messrs. Campbell & Potter's sawmill, where it became two, one leading up the river, and the other following the sandy ridge to Shin-gaw-ba-waw-sin-eke-go-ba-wot - now Ossineke. These Indian trails were of much importance to the early surveyors, land-lookers and settlers, being the principal means of communication by land between various parts of the country. These were called "paths" by the first explorers and settlers, and this is the reason for finding a "Pathmaster" in the list of the first ofiicers of the township of Fremont.

Geologists have represented the geological formation of the Lower Peninsula of Michigan, as a slightly depressed basin, having its center in or near Jackson and Ingham counties. As you travel any direction from this central point, you pass over the outcropping edge of various lithological strata, in a descending series, until you reach the granite formation; hence. Prof. N. H. A\'inchell, in his notes on the geology of the Thunder Bay region, published in the Pioneer, in 1870, says: "As one goes toward the north from Saginaw Bay, along the shore of Lake Huron, he passes ovei- the outcropping edges of rocks lower and lower in the geological series, until he reaches Lake Superior. The same is known of the Michigan side of Lake Michigan, northward from Grand Rapids." The writer believes this to be true, only in part, and as confined to the shores of the lakes, but not true in regard to the interior of the State. His travels and explorations in nearly all parts of the State, have led him to the conclusion that the interior of the northern portion of the Southern Peninsula has not been sufficiently explored by competent geologists, as to warrant them in coming to any definite conclusion concerning the geological structure of this region. A little observation will teach us that all rivers, wherever they run over stratified rocks, do not run with the dip, but over the outcropping edges. AVhenever they run with the dip, they seldom show the I'ocks; the streams are mostly sluggish, and the rocks generally covered with alluvial deposit. This being the case, the sources of rivers indicate the highest portion of country; and a little study of their courses and their descent, and the rocks over which they run, will give us an approximate idea of the geological structure ot the district of country through whicli tlu-y run. In referring to the rivers of the Lower Peninsula, we find the St. Josepb, Kalamazoo, and Grand rivers rising in the interior of the southern part of the Southern Peninsula, and carrying the summit level east of the center of the State, and running west and northwest with a moderate descent, over the outcropping edges of rocks, dipping slightly toward the center, empty their waters into Lake Michigan. The Shiawassee river, rising in the same vicinit}', runs north and mingles with the waters of Saginaw river, while the Clinton, Huron and Paisin rivere take their rise on the same summit level, and pour their waters into St. Clair Lake and Detroit river. After admitting that these rivers run over the outcropping edges of rocks dipping slightly toward the center of this Gfeologfical basin, then allow the writer to invite the reader to go with him into Roscommon, Crawford and Otsego counties, where we will reach another summit level, which is estimated to be one thousand feet above the level of the lakes. Here the Muskegon and Manistee, two large rivers, take their rise, and after running south and southwest, over ledges of rock dipping slightly to the northeast, discharge their waters into Lake Michigan. The Cheboygan, Pigeon and Black rivers rise in Otsego county, run north over ledges of limestone, dipping south, and lose themselves in the lakes of the Cheboygan river. The Thunder Bay and Au Sable rivers take their heads in small lakes in Otsego and Crawford counties, run east, with a rapid descent, over outcropping rocks, which dip to the west and northwest - with some local exceptional dip to the east, near Thunder Bay - pour their waters into Lake Huron. The Tittabawassee river, commencing in, and running near Roscommon county, runs south, and loses itself in Saginaw river. The Boardman, Elk and Pine rivers, take their sources on or near the summit level, and run west, into Grand Traverse Bay and Lake Michigan. Here we have another well defined geological basin, which, to practical geologists, is very little known, and especially that portion comprising the counties of Alpena and Montmorency. In 1859 and 1860, Prof. A. Winchell made some geological explorations in Alpena county and its vicinity, and subsequently it was visited by Prof. N. H. Winchell, but neither of them carried their explorations far enough to determine, in the faintest degree, the geological character of Alpena county; and they are not certain in regard to the super-position of the rocks, or the groups to which they belong. But the most important fact, entirely overlooked by geologists, in regard the geological formation of the Lower Peninsula, is the depression between those two basins. A line drawn from the mouth of Saginaw river to the month of the Muskegon river, passes nearly in the bottom of a synclinal valley between the two places. The Tittabawassee river running south from the north- ern basin, and the Shiawassee river ruiiuiiig uorth from the southeru basin; these rivers, with their branches, and other streams, establish the important fact that there is a depression running entirely across the Southern Peninsula, near its center, and dividing it into two parts or basins. This being a fact, we find the gypsum beds at Alabaster, and coal at Bifle river, to belong to the northern basin. Prof. N. H. Winchell says, in one of his notes to the Alpena County Pioneer, published in 1870: "There are various interesting [)roblems, yet unsolved, connected with the geology of the Thunder Bay region. The foregoing 'notes' have merely indicated the outlines of its prominent features. These indications even, are too often based on conjecture, rather than actual observation." Although the explorations now made are indefinite and of no available benefit to the county, yet they afford important suggestions, and will assist materially in any further survey; and, therefore, the writer has copied from the reports, all that he deemed of any probable value. In the groupings of the rocks in this region of the State, all the reports are vague and ambiguous, if not contradictory.

Prof. A. Winchell, in his report for 1850 and 1800, says: "The elevated limestone region, constituting the northern portion of the Peninsula, consists of the higher members of the Upper Helderburg Group, which gradually subsides toward the south, and in the southern part of Cheboygan county, as nearly as can be judged, sinks beneath the shaly limestones of the Hamilton Group." In the '"Atlas of the State of Michigan," Winchell calls tliesa limestones the "Little Traverse Group," and says: "This is composed chiefly of the Hamilton Group proper, of tlie New York geologists; but as the lower limits of the Hamilton have not yet been clearly fixed upon in the State, we a[)ply the above terms to a series of limestones outcropi)ing in the vicinity of Little Traverse Bay and Thunder Bay, and constituting physically a single mass. They have been tlie sub- ject of considerable study. In 1860, we made an ofl&cial survey of the Little Traverse strata; in 1866, a special survey and report, and in 1869, the ground was again officially examined, and as the result of all our studies, we submit the following generalized arrangement :

The total thickness was set down provisionally at 141 feet, which is probably too low. This grouping will apparently hold good over extensive region. On the Geological Map of Michigan, this group occupies the shore north from Little Traverse Bay to Thunder Bay, and round the bay as far as Ossineke. Prof. N. H. Winchell says: "The Hamilton limestones and shales, and the Huron shales, furnish the geological basis of the Thunder Bay region"; but he is somewhat puzzled in regard to the arrangement and super-position of the various strata, as will appear by his remarks, before quoted, and by the following to the Pioneer: "It has been remarked that the natural dip of the strata is toward the center of the State, in all places. This, however, is so slight as to be almost imperceptible to the eye; and hence, the natural beds generally appear horizontal, unless local causes have produced exceptional dip." Now, it has been found that rocks which underlie the Thunder Bay district are much affected by an exceptional dip. Along the lake shore, and in the limits of Thunder Bay, the exceptional dip eastward is always found. This is true as far north as Niue Mile Point, but it is not noticeable within Thunder Bay, and as far inland as Broadwell's mill, dip toward the bay. This downthrow of the rocks accounts for the occurrence of higher members in the Hamilton at the mouth of Thunder Bay river tlian at the "Big Rapids," thirty miles west. Prof. A. Winchell, in his report of ISoO-'GO, page 69, says: "On the east side of Thunder Bay Island, the rocks of the Helderberg group are seen overlain by a black bituminous limestooe, abounding in Atrypareiicularis, and numerous other Brachiopods allied to the types of this group, (Hamilton). The locality furnishes, also, two or three species of trilobites, (a) Favosiies. a large coral allied to Acervulariu, and some small fish remains. The same beds are again seen at Carter's quarry, two or three miles above the mouth of Thunder Bay river, and here it contains the same fossils. It is seen again on the south shore of Little Ti-averse Bay, replete with Brachiopods and Bryozoa, and is here eighteen feet thick. The exact order of super-position of the rocks constituting the Hamilton group, has nowhere been observed. The bluffs at Partridgfe Point, in Thunder Bay, are believed to come in next above the bituminous limestones of the localities just cited. The rock here is, at bottom, a bluish, highly argillaceous limestone, with shaly interlaminations, the whole wonderfully stocked with the remains of Bryozoa, and not a few encriuital stans. Above these beds, which are but five feet thick, occurs a mass of blue shale, six feet thick ; still higher is a massive limestone, below filled with Bryozoa, encrinites and Brachiopods; above, little fossiliferous, the whole with interlaminations of clay. At the upper rapids of Thunder Bay river, still a different but entirely detached section was observed, and it is yet impossible to collocate it with the others. At the upper ra[)ids - northeast quarter of southwest quarter of section 7, town 31 north, of range 8 east - on tlie south side of the river, limestone is seen in a bluff fifteen feet high, dipping east-southeast about five degrees. The whole section expoeed is twenty-five feet, made up as follows, from above:

6. Limestone, dark bluish, very fine grained, hard, compact and heavy, with a few reddish streaks and spots, and some encrinital stans and shells, and a few crystals of spar interspersed with occasional seams of the same, in the form of dog-tooth spar. Would make an excellent building stone, and probably would receive a fine polish - 6 feet.

5. Limestone, gray, crystaline, thick bedded, seen in bottom of river. This rock resembles fragments seen at the highest level above the lower rapids - 2 feet.

1. Calcarious shale, with fossils, forming the bed of the river. The dip at this place is abnormal, and evidently local. The true geological position of the rock must be determined by future investigation. The rocks of the Hamilton group are traced from the south shore of Little Traverse Bay, to near the outlet of Grand Traverse ^s.j. In speaking of the Huron group he says: "At Sulphur Island, in Thunder Bay, not more than a mile east-southeast from Partridge Point, is found a black bituminous slate, which is believed to overlie the fossiliferous clifFs at the latter place. No undisturbed strata are to be seen on the island, which consists of a mass of fragments, rising a few feet above the water. These slates, or shale, burn with considerable freedom, and it is stated that combustion started from camp fires has, in several instances, continued spontaneously for man\^ months, in one case sixteen months. The cinders resulting from these fires, are still very conspicuous. These shales furnish no fossils, except a few vegetable impressions, resembling Calamifes, and some very indistinct impressions of shells. Pyriteous uoctules and septaria are quite common. At Squaw Point, on the main laud, south of the island, near the residence of the old Indian Chief Zwanno- Quaddo, the black slates are found in places, in a clitf ten feet high. The exposed surfaces are very much discolored by oxide of iron. On the opposite side of the State, the black shales are seen at the southeast extremity of Mucqua Lake, in Emmet county; on the north side of Pine Lake, section 3, town 33 north, of range 7 west ; near the outlet of Grand Traverse Bay, section 3, town 32 north, of range 9 west, and a few miles south of there, and again near the head of Carp Lake, in Leelanau county. The greatest observed thickness in this part of the State, is twenty feet."

From the foregoing statement, we draw the very probable conclusion, that three distinct kinds of rock are found outcropping on and near the shores of Thunder Bay; that the carbonaceous limestones belong to the Helderberg or Little Traverse group; that the black bituminous limestones belong to the Hamilton group, and the black slates, seen at Squaw Point, belong to tlie Huron group. That an exceptional dip of the'focks exists in many places in the vicinity of Thunder Bay, and that tliey are much disturbed and displaced. The limestones termed the "Little Traverse Group," compose the surface rock on and near the lake shore, from Little Traverse Bay, northwaixl to Thunder Bay. In Cheboygan county, they reach as far south as the small lakes of Cheboygan river. In Presque Isle county, they probably reach as far west as the western extremity of Long Lake; and they cover most of that portion of Alpena county north of Thunder Bay. These limestones lie nearly horizontal, as observed along the shore of Lake Huron, and measured from the level of the lake. The high bluffs on the lake, at Crawford's Quarry, are about sixty feet high, and the one opposite Middle Island is of about the same height. The rock from here south, gradually subsides, until it reaches Little Thunder Bay, where it forms an escarpment abutting on the bay, about thirty feet perpendicular. They probably dip slightly toward the center of the northern basin, with some local exceptional dip in the vicinity of Thunder Bay ; but the western limits of their disappearance, under higher formations, have not been determined. These limestones are fine grained, highly crystallized and handsomely clouded, by the unequal distribution of the fossils and bituminous matter they contain. They are susceptible of a high polish, and when the large corals - especially the Favose and Cyathophylloids, which are abundant - are cut and polished, they present a very beautiful and agate-like appearance. Some years since a quarry was opened near Adams' Point, by Mr. Crawford, and is now known as Crawford's Quarry; and subsequently another quarry was opened nearly opposite Middle Island, by Mr. Litchenberg, and large hopes were entertained at the time, that samples would be found large enough to place the Lake Huron marbles with the most esteemed varieties; but no such samples have yet been found, and it is extremely doubtful whether they ever will be, as tHe rock is very much shattered. If the black bituminous limestones spoken of, belong to the Hamilton group, then this group of rocks in the Thunder Bay region is inconsiderable, not being in any known place more than six feet in thickness; and the same may be said of what is known of the Huron slates noticed at Squaw Point, whose aggregate thickness would probably exceed one hundred and twenty-five feet. Townships 31, 32 and 33 north, of ranges 6, 7 and 8 east, are remarkable for the abnormal and broken condition of the rocks. Ledges with large cracks and cavernous fissures, sink-holes or basins, in many of which streams of considerable size disappear, and exceptional dip in the rocks in various directions. A ledge of limestone, fifty feet high, occurs in the south part of section 35, in town 33 north, of range 7 east, faced on the north by a small lake, where can be seen large cracks and cavernous partings partly filled with detritus. These openings in the rocks run with the strike, sometimes for one-fourth of a mile. The dip could not be well ascertained. North of the partings, the rocks were much broken up, but south of the partings they dip in some places, slightly to the southwest. The strike bears southeast for about half a mile, in a well defined cliff, and then becomes very much broken and irregular, and which is very distinctly marked on the section line between sections 1 and 2, in town 32 north, ot rano^e 7 east. This ledore is traced in a northwest direction, into the northeast quarter of section 33, where it is about fifty feet high, and faced on the northeast by a long but narrow lake, apparently very deep. Here, again, are large partings in the rocks, and cavernous chambers, similar to the former, but the rocks are more broken and irregular. Here the dip appeared to the west, and the strike bending round the west side of the lake, had a trend southeast and north twenty degrees west. In the northwest quarter of section 16, town 32 north, of range 7 east, occurs a similar ledge, about twenty feet high, and also faced on the northeast by a small lake. Here are partings similar to those first mentioned. In the northwest quarter of section 14, in town 32 north, of range 7 east, near the section line, is a very singular basin. It is nearly round, two hundred feet or more in diameter, and about seventy feet deep. It was tunnel-shaped for about forty feet, and then the rocks became perpendicular; reposing at the bottom in what appeared like a cavern, was a small lake of nice, clear water. The writer did not examine the rocks, nor did he ascertain whether the water in the lake was in motion, or in repose. In the southwest quarter of section 5, in the same town and range, is a stream eight feet wide, which approaches from the northwest, a clifF of limestone, about twenty feet high, and at the foot of this cliff is an irregular cavernous looking basin, about thirty feet deep, into which the stream descends and disappears at the bottom. But the most remarkable basin in this vicinity is the one known as "Sunken Lake," on the west side of section

32, in town 33 north, of range 6 east. This is a wonderful and interesting locality, and afPords a key, when placed in skillful hands, to unlock many, if not all, the geological mysteries attached to the Thunder Bay region. When the writer visited this beautiful and interesting spot, in 1866, he was exploring for pine timber, and was not prepared, and did not examine anything critically or geologically. All of his measurements and descriptions are only approximate, and are given to assist those who hereafter may desire to examine the several localities, from curiosity or for scientific purposes. A few rods west of Sunken Lake, at this time, was a sink-hole of recent formation. It was oval in form at the top, its major axis being about one hundred feet over, was perpendicular on its west side, and about seventy feet deep, with water at the bottom. Commencing at the bottom and reaching up the side of the basin for thirty feet, was a coarse grained, buff colored, smooth, compact, argillaceous sandstone, and appeared to be the side of a fault in the sand rock. Reposing upon this was about three feet of black slates, similar to those met with at Squaw Point; and resting upon these slates, and reaching to the surface, is a laminated limestone, from thirty to forty feet thick, well and variously stocked with fossils. Near the west side of this ''hole in the ground,''^ the limestones commence to dip to the east, and plunge over the edge of the sandstone, at an angle of about sixty degrees, to the bottom of Sunken Lake, which is not less on the west side than seventy-five feet deep. The rock continues under the lake as far as it could be traced. Here is a very singular and extraordinary exceptional dip to the east; but what is still more singular, is, that the limestones are not cracked or broken, but lie over the precipice made by the faulted underlying rock, as though it had flowed over them in a soft state, and hardened on its passage, leaving a hollow space between them and the margin of the rock, forming a channel of a subterranean river. The strike of these rocks was traced only about forty rods, bending to Ibe east on the bottom sides of the lake, and forming the west half of Sunken Lake. Between this downthrow and the more northern limestone is a valley filled with drift, composed of very coarse gravel, sand, clay, etc., with a few large boulders. The North Branch of Thunder Bay river, which is thirty feet wide near Sunken Lake, and capable of floating saw-logs for twenty or more miles above the lake, in making its channel to Thunder Bay river, passes over a portion of this drift bed; and that portion of the drift betAveen the channel of the river and the drift flanking the west side of the lake, being very porous, filled with water from the river, and was pressed with great force through the small cracks and seams in the limestones. In time these holes through the rocks were made large enough to pass sand and small gravel, and then commenced the hollowing out of the lake. The limestones becoming denuded, were split and crumbled by the frosts of winter, presented additional mouths to invite water from the river, until it quit its old bed, turned at right angles with its old channel, cut a new one for half a mile to the lake, and after making a few gyrations, sank beneath the rocks, to pass in subterranean darkness to the waters of Little Thunder Bay, where it is indefinitely ascertained that it emerges. The apertures in the rocks are not yet large enough to admit the whole river in time of a freshet, and the surplus water returns to its old channel, affording the lumbermen a small chance to run their logs past this difficult place. This subterranean stream, in all probability, follows the strike of the faulted sandstone, which we think bears about east-southeast from the lake. At the same time the writer examined Sunken Lake, he discovered a verj- interesting sink-hole, or basin, somewhere about southeast from the lake, and thinks it was between sections 15 and 10, in town 31 north, of range 0 east. It was situated in the midst of a heavy growth of sugar, beech and hemlock timber. The hole was nearly round, and about two hundred feet in diameter. The alluvium and drift was about fifty feet deep, and the cavern below was spacious enough to take this immense mass of matter and the large forest trees, and hide them in the chambers below; it had fallen entirely out of sight. In sinking the first well in Alpena, the lithological structure was noted for 64^ feet, and it is remarkable that after passing through the alluvium and drift for 30 feet, and through only two feet of limestone, a quartz rock was reached, 18 feet thick, carrying copper, and perhaps gold. If the records be true, the chances for gold would be better than for salt from the Saginaw basin. Taking all these facts into consideration, we are drawn to the inevitable conclusion that the Saginaw salt group and the carboniferous limestones found in the lower basin, compose the nine hundred feet of rock piled up above the sandstones seen at Sunken Lake. That the Saginaw salt lies in a valley between the two basins, and extending from Saginaw Bay to Muskegon. That Alpena city and its immediate vicinity is on the outcropping edge of the northern geological basin, and below the Saginaw salt group; and that if salt is ever found here, it will be taken from the Onondaga salt group of rocks. And now that roads have been made into the interior of the county, affording good facilities for reaching every part of it, that a few hundred dollars would be well expended by the county, in employing a competent geologist to make a proper survey of this most interesting portion of the Southern Peninsula.