are of interest. He says: "If it be true that bed No. 4 is the northern extension of the Louisiana limestone, then the Chonopectus sandstone and the underlying shales would be included in the Devonian according to Keyes' interpretation of the Kinderhook." Now "bed No. 4" is the Productal limestone. It is above what in the Iowa and Missouri reports has been regarded as the Hannibal shale, and if the most recent and detailed stratigraphical evidence* is to be relied upon, it is very near the top of the Kinderhook, instead of at the very base of that formation. According to the statement just quoted, the Chonopectus sandstone, which immediately underlies the Productal limestone or is separated from it only by a very thin Coralline zone, would then be parallelled with the shales underlying the basal member of the Kinderhook (or Louisiana limestone), at the type locality of that formation. However, there are grave difficulties to overcome before this opinion is fully substantiated, and Weller refers specifically to no data from which his inferences are drawn. Concerning the geological position of the Chonopectus fauna alone Weller farther remarks: "Taken as a whole a large number of the total 81 species recognized in the fauna, have Devonian and not Carboniferous relationships, but this is not sufficient evidence upon which to establish the Devonian age of the fauna. In general, in paleontologic interpretation, the initiation of a new invertebrate faunal element is of greater importance than the holding over of a much larger element from an older fauna, and on this principle the strongly Carboniferous element among the brachiopods of the Chonopectus sandstone is to be considered as weightier evidence than the holdover pelecypods and cephalopods.”† Of the six zoological classes of organisms, which the 81 enumerated species go to make up, all but the brachiopods have admittedly a strong Devonian aspect. Of the score of brachiopod species one-half are certainly indecisive as to exact age, and of the other half there is about equal division between Carboniferous and Devonian types. There is therefore *Journal Geology, Vol. VIII, p. 317, 1900. †Trans. Acad. Sci., St. Louis, Vol. IX, p. 126, 1900. one-fourth of the brachiopods that might be considered as forming a new faunal element. The importance of the introduction of a newer, or geologically younger faunal element is fully recognized, but it is not believed that its appearance should entirely overbalance the existence of greatly predominating older elements. We can hardly consider a new faunal age to begin with every initial introduction of a new faunal element. Faunas have their beginnings far down in the depths of older faunas. They expand, displace the older elements and culminate. They decline and fade away far up among still newer faunas. We have analogous examples in the progress of nations. The initiation of a new element does not indicate a new dynasty. A new political movement has its birth midst a multitude of conflicting ele It may grow in importance and finally displace the existing government. Only when it has overcome the older ruling powers is a new régime inaugurated. Not until then does the nation require a new name. There are long steps between the initiation of a new element and the initiation of a new régime. If a new régime, a Carboniferous régime, is initiated at the basal horizon of the Louisiana limestone the actual evidence afforded by the 81 species enumerated from the Chonopectus sandstone, which is regarded as pre-Louisianan in age,* appears to be far from demonstrating it. The consideration of the other and related faunas may give more substantial proofs. However, on this point it is probably best to suspend judgment until the "Faunal Kinderhook Studies" now in progress are completed, since for the first time evidence along these lines promises to be exhaustive. The still later statement in which Weller* regards all of the Burlington section below the Productal limestone, (Bed No. 4) as older than the Louisiana limestone, suggests another interesting consideration. The inference is that this writer considers the most marked faunal change to take place at the base of the Productal limestone. If the view I have already expressed be the correct one, that this horizon at Burlington is to be considerd as equivalent to the base of the Chouteau limestone farther south at Louisiana, as the stratigraphy seems. *Iowa Geol. Sur., Vol. X, p. 79, 1900. † Loc. cit. clearly to indicate, and not the base of the Louisiana limestone, then there is perfect agreement in Weller's conclusions regarding the most notable faunal change in the Burlington section and my own in the Louisiana section taking place at the same horizon. In regard to the lithological character of the Productal limestone at Burlington being the same as those of the Louisiana limestone the real resemblance is certainly very remote. Few would ascribe lithographic properties to it as in the case of the Louisiana stone. While at Burlington it is the only bed the general appearance of which at all approaches the Lithographic or Louisiana limestone there is not very much to suggest identity. If the two limestones are one and the same there must be very remarkable and wholly anomalous stratigraphical phenomena existing between the cities of Keokuk and Burlington. There is one feature in which Mr. Weller's recent work corroberates my own results in a most conclusive manner. Kinderhook as a geological title is no longer available and valid. If the Chonopectus sandstone immediately beneath the Productal or Fragmental limestone at Burlington is pre-Louisianan in age, as Weller suggests, it is ascribing an age much older than is even intimated in any of the recent Missouri and Iowa reports. In this connection certain recent records of deep wells are not without interest, in attempting to parallel the Burlington section with that of Kinderhook and Louisiana.* The evidence derived indicates that the lowermost member of the typical Kinderhook, the Louisiana limestone, which is 60 feet thick at the type locality, gets thinner and thinner northward until at Keokuk it is not more than 10 feet thick, and doubtless fades out altogether before Burlington is reached. On the other hand the median member of the Kinderhook, the Hannibal shale which is 70 feet thick at the type locality retains its full thickness at least as far north as Keokuk, and at Burlington appears to merge downward with the shale which farther south underlies the Louisiana limestone. The latest faunal correlation appears to be closely in agreement with this stratigraphical interpretation. *Journal Geology, Vol. VIII, p. 317, 1900. REVIEW OF RECENT GEOLOGICAL LITERATURE. A Contribution to the Geology of the Northern Black Hills. Thesis Submitted in Partial Fullfillment of the Requirements for the Degree of Doctor of Philosophy, in the Faculty of Pure Science, Columbia University, June 1899. By JOHN DUER IRVING. [Annals N. Y. Acad. Sc. Vol. XII, No. 9, pp. 187-340, pls. V-XVI, figures 5-20.] This paper constitutes a valuable addition to the geology of the Black hills. Its purpose is the extension of stratigraphic and petrographic detail rather than the development of new theoretical knowledge. The district described exhibits most strikingly many phenomena whose origin is due to the vast intrusive masses which form the predominating rock of the region. The Black hills topography strikingly illustrates the relation of degradation to geological structure. In the western area the country rock consists of horizontal Carboniferous strata; in the plateau which these strata form streams have cut precipitous canyons, leaving flat table-like divides. Farther east the topography consists of the conical hills and sharp irregular ridges with complicated drainage, characteristic of regions which have been the seat of igneous activity. Dr. Irving finds Algonkian, Cambrian and Carboniferous beds. containing many intrusions. The character of the intrusion is found to be dependent upon the nature of the rock into which it is intruded; in the vertical slates and schists of the Algonkian only dikes are found; in the soft thinly bedded Cambrian shales, are sheets; the massive Carboniferous sandstones and limestones are penetrated by very few dikes and by some irregular masses which Dr. Irving regards as belonging to none of the ordinary classes of intrusion. In each case the intrusion has followed the direction of least resistance and subsequent erosion has left the dikes standing out as ridges and the sheets as laccoliths. found to present a large are the various kinds of Petrographically the intrusives are variety of types. The most abundant phonolyte which constitute the greater number of the laccoliths. Various types of rhyolytes, andesytes, dacytes, diorytes, lamprophyric dike rocks and amphibolytes are found. The Black hills have at least twice been the seat of prolonged igneous activity. The first period was previous to the metamorphism of the Algonkian and was characterized by the intrusion of sheets of basic rock, now represented by the amphibolytes. These intrusives were metamorphosed with the Algonkian strata, and together they were raised to a vertical position, hence the sheets now appear to be dikes. The second period of activity was post-Cretaceous and was marked by a highly alkaline series of intrusions. This series forms true dikes in the Algonkian and sheets in the Cambrian. It yet remains to be determined whether the lamprophyric dike rock (augite-vogesite) represents the final basic residuum of the alkaline magma, or whether it belongs together with the phonolytes and quartz-ægirite rocks, to a different series from the rhyolyte-andesyte rocks. In the district described gold occurs in the Algonkian, Cambrian, and Carboniferous, and in placers of recent formation. It occurs associated with pyrite; in quartz veins with silver and lead; and free. Silver is also found. Dr. Irving has covered only a portion of the region affected by the Black hills intrusions. In this field he has confined himself to description and to the farther elaboration of previously formulated hypotheses. The differentiation of rock magmas is a subject for which, as Mr. Irving himself states, this region is admirably calculated to provide data. This problem has been barely touched by him and it is to be hoped that additional data may be found from farther investigation of the Black hills and of the Bear Lodge mountains. When such investigation takes place Dr. Irving's determinations will be of undoubted value. I. H. O. The Moraines of Southeastern South Dakota and their Attendant Deposits; by JAMES E. TODD, U. S. G. S. Bull. 158, pp. 1–168. This volume is a preliminary report, treating of a relatively small portion of the Dakota loop of the great moraine. It furnishes valuable data upon several Pleistocene problems;-the origin of loess, the distribution of glacial drift, and post-Pliocene oscillations of the earth's crust. The greater part of the report is descriptive of glacial deposits in South Dakota and Nebraska. Two moraines are found, the outer one which extends to the Missouri river, marking the maximum extent of the ice in the second glacial epoch. Outside of this moraine deposits of a previous epoch are found; of these deposits loess is the most abundant. Mr. Todd discusses the formation of loess, believing it here to be of fluvio-lacustrine origin. The inner moraine represents a halt in the retreating ice and is much less prominent than the outer. Inside the second moraine is the flat of lake Dakota. Mr. Todd discusses the age of the trough of the Missouri river, and concludes that the evidence is in favor of a post glacial excavation. I. H. O. Elements of Mineralogy, Crystallography, and Blowpipe Analysis, from a Practical Standpoint, including a description of all common or useful minerals, with tests necessary for their identification, the recognition and measurement of their crystals, and a concise statement of their uses in the arts. By ALFRED J. MOSES and CHARLES LATHROP PARSONS. Octavo 414 pages, 664 cuts, new enlarged edition, $2.00, New York, 1900, D. Van Nostrand Company. The title describes this book fully. It is one of the interesting and valuable series of the science faculty of the School of Mines of Columbia University, New York, although, in this instance, Prof. Parsons is of New Hampshire College, Durham, N. H. Its design is for the student of the technical school and for all courses in mineralogy where mineralogy |