ARCHIV FUR NATURGESCHICHTE, Jahrgang 43, Heft 2. Untersuchungen über den Kaumagen der Orthopteren, von K. F. Wilde. Grundzüge zur Systematik der Milben, von P. Kramer.

THE GEOGRAPHICAL MAGAZINE. October. The Seat of War (with a map of the seat of war in European Turkey, by Keith Johnston). M. Dupuis' Explorations in Tongkin and Yunnan. Delta of the Yangtze River in China, by S. Mossman. A Description of the Island of Formosa, with some Remarks on its Past History, its Present Condition, and its Future Prospects, by J. Morrison. The Crozet Islands (South Indian Ocean), by L. Brine.

THE MONTHLY MICROSCOPICAL JOURNAL.- October. New Diatoms from Honduras. Described by A. Grunow. With Notes by F. Kitton. Some Additional Remarks on the Measurement of the Angle of Aperture of Object Glasses, by F. H. Wenham.

QUARTERLY JOURNAL OF MICROSCOPICAL SCIENCE. October. The Doctrine of Contagium Vivum and its Application to Medicine, by W. Roberts. Résumé of Recent Contributions to our Knowledge of Fresh-Water Rhizopoda, Part IV. Rhizopoda Monothalamia Monostomata, compiled by W. Archer. Loxosoma, by Carl Vogt. On the Minute Structural Relations of the Red Blood Corpuscles, by A. Boettcher. Contribution to the Minute Anatomy of the Epidermis in Smallpox of Sheep, by E. Klein. Notes on the Embryology and Classification of the Animal Kingdom, comprising a Revision of Speculations Relative to the Origin and Significance of the Germ Layers, by E. R. Lankester.

THE GEOLOGICAL MAGAZINE. October. Is Man Tertiary? The Antiquity of Man in the Roman Country, etc., by R. D. P. Mantovani. The Antiquity of Man, by J. R. Dakyns. Reversed Faults in Bedded Slates, by E. J. Hebert. The Geology of Sumatra, by M. R. D. M. Verbeek. The Migration of Species, by C. Callaway.

ANNALS AND MAGAZINE OF NATURAL HISTORY.. October. Studies on Fossil Sponges, I. Hexactinellida, by K. A. Zittel. On some New and Little Known Spiders from the Arctic Regions, by O. P. Cambridge. On the Changes produced in the Silicious Skeletons of Certain Sponges by the Action of Caustic Potash, by W. J. Sollas. Capture of a Right Whale in the Mediterranean, by A. Doran. Notes on the Pearly Nautilus, by G. Bennett. On a New Insect Pest at Madeira, by T. V. Wollaston. Remarks on Professor E. Haeckel's Observations on Wyville-thompsonia Wallichii and Squamulina scopula, by H. J. Carter.

POPULAR SCIENCE REVIEW. October. The Volcanoes of the Haute Loire and the Ardêche, by W. S. Symonds. Flint Implements, by C. C. King. The Song of the Cicada, by J. C. Galton. Caves and their Occupants, illustrated by the Bone Caves of Creswell Crags, by J. M. Mello. Meteorites and the Origin of Life, by W. Flight.

THE

AMERICAN NATURALIST.

VOL. XI. DECEMBER, 1877. - - No. 12.

THE CHINESE LOESS PUZZLE.

BY PROFESSOR J. D. WHITNEY.

THE appearance of the first volume of Baron F. von Richthofen's magnificent work on China furnishes us with a suitable opportunity to put before the readers of the NATURALIST a brief account of one of the most curiously puzzling geological phenomena which has ever been brought to the notice of the scientific world, the distribution and mode of occurrence of the so-called loess deposits of Northern China. The term loess is one in popular use in the valley of the Rhine for a peculiar loamy material 2 which occurs over a considerable area between Constance and the Belgian lowlands, having in places a thickness of as much as one or two hundred feet, and which is generally admitted to have been a lacustrine deposit, formed when the Rhine was swollen by the melting of the great Alpine glaciers, which then extended much below their present level and covered a far greater area than they now do. Important as this formation is in that region, it sinks into insignificance when compared with what is presented by the Chinese deposits of similar character.

The Chinese loess, like that of the Rhine, is an earthy substance of a brownish-yellow color, so tender and little coherent that it can be easily rubbed to a powder between the fingers. It is chiefly made up of argillaceous materials, with a small proportion of carbonate of lime; and it has also mixed with it more or less fine sand, the grains of which are quite angular. This sand, however, is small in quantity as compared with the argillaceous

1 China, Ergebnisse eigener Reisen und darauf gegründeter Studien, Erster Band, Einleitender Theil. Berlin, 1877.

2 Loess is very nearly the equivalent of the English word loam. Perhaps the best way to define it would be to say that loam when developed enough to become a formation of geological importance, and not a mere surface deposit, is loess.

Copyright, 1877, by A. S. PACKARD, JR.

portion. The most striking facts with regard to this material in China are its wide-spread distribution and its enormous thickness, facts which, taken in connection with its composition and structure, render its origin one of the most perplexing of geological problems.

First, as to its distribution. According to Richthofen, this formation is spread over a large part of the region drained by the Hwang-Ho or Yellow River, a name derived from the color of the material which this great stream is continually carrying in suspension towards the Yellow Sea, in which name we again recognize the coloration given by the particles of the loess, which itself is called by the Chinese hwang-tu or yellow earth. For nearly a thousand miles from the borders of the great alluvial plain of Pechele, through the provinces of Shansi, Shensi, and Kansu, every where to the north of the Wei, which runs along the northern base of the range of the Tsing-ling-shan, the loess may be followed up to the very divide which separates the basin of the Hwang-Ho from the region destitute of drainage into the sea. Towards the north, it reaches almost to the edge of the Mongolian plateau. Furthermore, it may be observed in the province of Honan, along the south side of the most easterly outliers of the Kwenlun, filling a large portion of the middle part of the basin of the Han, covering large areas in Shantung, and reaching southwards in isolated patches as far as the Yangtse. The area over which the loess spreads itself almost continuously is as large as the whole of Germany; while it is found in more or less detached portions over an additional area nearly half as large as that empire.

From the known topographical character of the loess-covered region, it will be recognized at once that the formation in question occurs at very varying altitudes, or that it is distributed without regard to the elevation of the surface on which it rests. From near the level of the sea up to six thousand feet and more above it, this characteristic material lies, covering valley and mountain slope, absent only on the crests of some of the higher dividing ridges. This extraordinary range of vertical position has not been given to the loess by changes of level of the land since it was deposited, for Richthofen declares that it clearly results from his researches that the relative position of the higher and lower portions of the region in question has not been changed since the deposition of the loess; although he believes that, as a whole, its eastern border has been depressed in altitude, the

coast-line formerly extending farther out into the sea than it now does. So much for the horizontal and vertical distribution of the loess, and now some of its structural conditions may be noticed.

It

Two peculiarities strike the eye of the observer at once on examining the material in question: in the first place, the entire absence of any indications of stratification; and, second, the tendency which it everywhere exhibits to cleave or crack in vertical planes. These peculiarities, however, would not make such a strong impression on the mind of the geologist if it were not for the enormous thickness of the deposit, which is usually several hundred and in places reaches fifteen hundred or even two thousand feet. To see such a mass of material, not of igneous origin, destitute of any indication of stratification, is something entirely out of the ordinary experience of the geological observer. would seem impossible that such a deposit could have been laid down except from water, and, if so, where are the lines of deposition, which never fail to make themselves visible in aqueous sediments? The problem, as will be seen, begins to present itself as a puzzle. But it may be asked, Is not this a deposit from water, in which, owing to some peculiar conditions, the lines of stratification have become obliterated? The answer to this is readily given in the negative, when on investigation it is found that this deposit, hundreds of feet in thickness, contains imbedded within its mass no fossil remains of marine or fresh-water origin, but only land shells mostly those of snails and occasional bones of land animals. It is evident, then, that this so-called loess is not similar in origin to that of the Rhine Valley, as indeed might easily have been inferred from its position at all elevations over plain and mountain side; but that it is a subaerial deposit.

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Apart from theoretical considerations of origin, which make this loess formation so interesting, there are other circumstances resulting from its mode of occurrence, which bear on the daily life of the people inhabiting these loess-covered districts, and so connect themselves with their agriculture, their roads, and their means of military defense as to be abundantly striking, even to the observer who cares nothing for geological problems, and to whom the absence of lines of stratification would not appear as a noticeable fact. The peculiar type of scenery which these great areas, covered by such a thickness of soft, easily eroded material, present could not fail to impress itself on the mind of the most careless observer. And we find that the main features of the landscape in the loess districts are closely connected in their ori

gin with the tendency which this material possesses — as already noticed to divide into masses separated by vertical planes; a peculiarity which is not properly cleavage, neither is it exactly what geologists call jointing, but something near akin to it. As a result of this tendency, we find that the rivers which run through the loess-covered districts are bordered by absolutely vertical walls of this material, sometimes hundreds of feet in height. Given the elements of great thickness of the deposits, extreme facility of erosion due to the softness of the mass, and the tendency to vertical cleavage, and it can easily be imagined that the resulting forms left from the action of erosive agencies must be extremely complex and peculiar. Indeed, as described by Richthofen, the loess-covered region is certainly one of the most curious portions of the earth's surface. It somewhat resembles the Colorado plateau, in being deeply and intricately furrowed by drainage channels of great depth, and proportionately very narrow. In the Colorado region, however, the walls of the cañons, as these gorges are there called, are never vertical, though usually quite steep, and the material on which the water exercises its erosive power has a greater variety of texture and color than that offered by the loess, which is remarkably homogeneous from top to bottom. The difficulty of traversing such a region, or even of engineering roads through it, can readily be imagined. It is not so much of a task to keep on one main divide between two systems of gorges; but to go across the country in any fixed direction is almost an impossibility. Tunnels and spiral stairways in the mass of the loess must often be resorted to. In short, the configuration of the surface is, as Richthofen remarks, most fantastic and curious. "Wide chasms are surrounded by castles, towers, peaks, and needles, all made up of yellow earth, between which gorges and chasms radiate labyrinthically upwards into the walls of solid ground around. High up on a rock of earth, steeper than any rock of stone, stands the temple of the village, or a small fortress which affords the villagers a safe retreat in times of danger. The only access to such a place is by a spiral stairway dug out within the mass of the bluff itself. In this yellow defile there are innumerable nooks and recesses, often enlivened by thousands of people, who dwell in caves dug out in the loess.1"

Millions of human beings live in habitations excavated in this 1 Richthofen, Letter on the Provinces of Chili, Shansi, Shensi, and Sz'-chwan. Shanghai, 1872.