calcite, but this may represent a secondary deposition.* In his report of 1860, Winchell refers to this as an acicular structure and infers that it is characteristic of gypsum. Rominger uses the term acicular also in describing the Ida rocks and calls attention to the widespread character of the phenomenon, but does not name the substance by which it may have been produced. It is to be noted that the crystals, however, were not needle shaped and only the cavities in cross-section give this appearance. In weathered specimens there are shown plainly the frondescent structures associated with the spherical granules in the beds of oölite previously described. These make up the body of the rock in places, their dim outlines showing in the solid dolomite. The oölitic granules are much obscured but are recognizable, proving that this bed is, in part at least, an oölite. In position it is the equivalent of the bed struck in the Nicol's well, above mentioned, and in the Rath quarry. The characteristic choco. late brown blotches are locally abundant. No fossils were collected from any of the strata. Rominger determined the amount of calcium carbonate in a sample to be 59% and of magnesium carbonate 39%. Underlying this bed is the so called "second formation," which is well exposed in some of the deeper excavations of the quarry. This is a firm dolomite, dark when damp, but drying to a light gray. The surface of the bed is rough and irregular and the upper three to four inches porous and open, containing numerous moulds and casts of gasteropods, brachiopods and corals. Distinct lamination is to be seen in places. A drill core of this and the deeper beds was taken out in 1895; but the cores had been disturbed and some lost, so that the record obtained from them was unsatisfactory, except in a few cases where the depth had been penciled upon the core at the time of its removal. A silicious dolomite, streaked with blue, was found to overlie the bed of white sandrock struck in the Nicol's well. This latter appears to be six to seven feet thick, but contains much dolomitic matrix, and extends from about twenty-four to thirty feet of depth in the well. Beneath this bed lies a compact silicious dolomite, streaked and blotched with blue, which in turn, cannot be many feet above the surface of the Sylvania sandstone. Just west of the Davis quarry there are two small excavations which have entered the "first formation" to a depth of two to three *I am inclined to refer it to calcite. It seems to be a widespread phenomenon at about this point in the geological scale, as I have noticed it frequently in the Upper Peninsula. See also Rominger Geol. Sur. Mich., Vol. I, Part III. p. 27, and Dana's Geology, p. 247 of the first edition. L. feet. The larger lies just west of the highway and north of the railroad upon the property of Michael Voight and the other to the south, upon the opposite side of the railroad, and belongs to Byron Wilcox. § 7. Lulu quarry. In Sec. 16, N. W. 4, N. W. 1, the rock rises to within three to five feet of the surface, upon land now belonging to Henry McCarthy. Rock for local building purposes was removed here fifty years ago and the main part of the quarry for many years was in possession of Henry Y. West, now of Lulu. The excavation contained too much water at the time visited to allow a satisfactory inspection of the beds, but they were seen to correspond with those penetrated by the drill in the Ida quarry. The strata have here been thrown into a fold giving a high local dip to the east and west by south. This might be a good place to test for oil. A v-shaped break extends northeast and southwest across the quarry on either side of which the strata are said to overlap "like shingles on a roof." The quarry has followed this break for nearly one hundred yards and the layers have been removed for a short distance on either side, the west wall furnishing the best exposure. An upper layer nine to ten inches thick, is a buff dolomite, highly charged with rounded sand grains, varying considerably in size. Beneath is a twelve inch layer of a less gritty, tough, light gray dolomite, succeeded by a white sandstone layer of the same thickness. These three feet represent the lower portion of the sandrock of which cores were obtained in the Davis and Nicol's wells. The main quarry rock consists of those dolomites which lie between this bed and the Sylvania proper, of which eight to nine feet have been exposed. These are compact gray dolomites, more or less mottled, streaked and blotched with rather vivid blue coloring matter. Some of the rocks much resemble in appearance, as Rominger suggests, castile soap. According to Mr. West there are two acres here over which rock could be easily quarried, lying within one quarter of a mile of the Ann Arbor R. R. An analysis of the dolomite gave Rominger the following: Calcium carbonate 54% 4 § 8. Little Sink quarry. A small but interesting quarry has been opened upon the eastern edge of what is known as the "Little Sink," to be later described. The excavation lies in the S. E. 1 S. E. 1 Sec. 2, Whiteford township upon land owned by Morris Cummins. Over an area of ten to fifteen acres the rock lies very near the surface, so that the scanty soil is practically unfit for agricultural purposes. The rock in some places is entirely bare of soil, while in others its thickness varies from one to two feet. Upon the west side of the quarry there is practically no stripping, but this reaches a thickness of one to one and one-half feet upon the eastern side. In passing southwestward from Lulu the surface of the rock is depressed, covered with a heavy belt of sand, and next reappears here at the surface in consequence of having attained an elevation above sea level of about 670 feet. The quarry is nearly equi-distant from the Ann Arbor R. R. and the Toledo-Adrian branch of the Lake Shore railroads, being about five miles from each in a direct line. In consequence, the markets are entirely local the demand being simply for building stone. The present quarry was opened about thirty-five years ago, but previously stone had been superficially quarried for building purposes and for the manufacture of lime upon a small scale. The opening is in the form of an irregular quadrilateral about 100 by 50 feet, and the strata have been penetrated from nine to ten feet. The water enters the crevices of the rocks through which it drains away except in the early spring, when the entire region is liable to be flooded. Two fairly distinct beds may be recognized which overlie a pure white sandrock in which the grains are cemented by a dolomitic matrix. A comparison of these beds with those previously described shows that they are intermediate between the beds exposed in the Ida and Lulu quarries, being, indeed, those penetrated by the drill in the Davis quarry before the white sandrock was reached. The Lulu strata will then be exposed here by going deeper. The uppermost bed is thin-bedded and varies in thickness, within the limits of the quarry, from three to five and one-half feet. Typically it is a compact, tough, gray dolomite, showing a rather bright greenish stain in places. Towards the surface it is fissured and weathered considerably, showing a rusty iron coloration. The rock is penetrated with numerous channels which seem to be the preserved bur |