Alpine Land Research Articles

Insolation, Topography, and Settlement in the Alps

THEN on a mountain summit one seldom tires of watching the movement of sunlight and shadow over the landscape. Even if the day is cloudless there is constant fascination in the dwindling and shifting of the shadow patterns as the morning advances; in their widening and merging into new forms as the sun sinks (Fig. 2). These changing forms give the geographer food for thought; for he knows well the value of solar radiation to dwellers in mountain regions.' He knows that crops that ripen early on slopes exposed to the sun may fail to ripen at all on the opposite side of a valley. He knows that in the Alps north-facing mountain slopes are generally left to forest but that pastures extend high on south-facing slopes. These facts he recognizes in general terms. The shifting play of shadows, moving as they do in accordance with rigid mathematical laws, may suggest to him the possibility of precise investigation of the interrelationships of insolation, topography, and human life in mountain regions. The present study is a development of this thought. In regions of high altitude and where Alpine land forms predominate, insolation is especially important as a geographical factor, partly because the solar radiation received at the earth's surface increases with altitude and partly because the boldness of the topography causes sharp local contrasts in the duration and intensity of insolation. Methods of map analysis are suggested in the following paragraphs as a means of discovering and isolating the effects of topography on insolation. Three types of map have been selected to show correlations of geographical significance for the particular regions under discussion. The maps show (I) the winter noonday shadow area, (2) time periods of sunshine at the equinoxes, and (3) the noonday intensity of insolation at the equinoxes, all as determined by topography. How these maps were constructed will first be explained; then the maps themselves will be interpreted in the light of what they reveal; and finally some further refinements of the method will be suggested. The time-period and intensity maps, it must be observed, show potential, not actual, amounts of sunshine. Given clear weather from sunrise to sunset, the frequencies indicated would be experienced

Alpine Land Forms of Western United States

Introduction Land forms of the alpine portions of western United States are ordinarily described as though they were chiefly the product of erosional and depositional processes familiar at lower elevations, their characteristic variant being Quaternary glaciation. In reality, this conception is far from representing the actual facts. With all glacial forms subtracted, alpine landscapes would be strikingly different from landscapes of lesser elevation in similar latitudes. In many respects they resemble the desert, but their closest relatives exist in Arctic borderlands. It is the purpose of this paper to describe some of the more common alpine land forms and to emphasize the importance of certain significant processes. It is written in the light of field experience extending through the past 12 years and covering many of the highest regions in western United States, chiefly in California, Nevada, Colorado, and Wyoming. Field work in northeastern California in the summers between 1920 . . .

The Oxford Geographies

WHEN a school-book treats of the geography of the whole world in less than 300 pages of large, clear print, interspersed with abundant diagrams, its claim to compete with the ordinary class-book must be based on the substitution of quality for quantity, wise selection and arrangement for all-including comprehensiveness. The book before us may fairly make such a claim. There is nothing of the gazetteer about it: its method is that of connected description; in place of statistical tables we have an abundance of distribution-maps, and continents and countries are divided according to physical features more than by political boundaries. Thus in the case of England the counties are entirely ignored, and the pupil is spared the necessity of learning as many “facts” about Oxfordshire as about Lancashire. So, too, in the case of Europe, there is a special section on Alpine lands, which renders possible a connected account of the railway routes across the Alps, and should prevent the common misconception of the Alps a coextensive with the political area of Switzerland. The Oxford Geographies. Vol. ii. The Junior Geography. By A. J. Herbertson. Pp. 288. (Oxford: Clarendon Press, 1905.) Price 2s.

IX.—On the Glacial Succession in Europe

For many years geologists have recognised the occurrence of at least two boulder-clays in the British Islands and the corresponding latitudes of the Continent. It is no longer doubted that these are the products of two separate and distinct glacial epochs. This has been demonstrated by the appearance of intercalated deposits of terrestrial, freshwater, or, as the case may be, marine origin. Such interglacial accumulations have been met with again and again in Britain, and they have likewise been detected at many places on the Continent, between the border of the North Sea and the heart of Russia. Their organic contents indicate in some cases cold climatic conditions; in others, they imply a climate not less temperate or even more genial than that which now obtains in the regions where they occur. Nor are such interglacial beds confined to northern and north-western Europe. In the Alpine Lands of the central and southern regions of our Continent they are equally well developed. Impressed by the growing strength of the evidence, it is no wonder that geologists, after a season of doubt, should at last agree in the conclusion that the glacial conditions of the Pleistocene period were interrupted by at least one protracted interglacial epoch. Not a few observers go further, and maintain that the evidence indicates more than this. They hold that three or even more glacial epochs supervened in Pleistocene times. This is the conclusion I reached many years ago, and I now purpose reviewing the evidence which has accumulated since then, in order to show how far it goes to support that conclusion.

Scientific Serials

Jahrbuch der k.k. geologischen Reichsanstalt. Band xxiv. Nos. 1 and 2.—The first article in No. 1 is by Dr. A. Redtenbacher, and treats of the stratigraphical relations of the mesozoic formations as developed in the district of G ms, near Hieflau. The second paper, by Dr. C. Doelter, gives so ne account of the Siebenbürgischen metalliferous mountains. The district described lies south of the river Arranyos, between Offenbánya and Bistra, as far as the Maros. The formations developed in this district consist of (1) crystalline, metamorphic, and eruptive rocks (gneiss, crystalline limestone, granite, diorite, syenite); (1) Jurassic and cretaceous (limestone, meliphyre and augite porphyry, sandstone, chalk, &c.); (3) Tertiary (comprising, besides various fossiliferous deposits, such igneous rocks as hornblende-andesite, augite-andesite, basalt); (4) alluvium. A sketch-map accompanies Dr. Doelter's communication.—Herr R. Hörnes contributes a paper entitled “Tertiary Studies,” in which he gives an account of the mollusca met with in various Tertiary deposits (as at Kischeneff, Jenikale, &c.) A number of the species described are new to science. Four excellent plates illustrate the paper.—Dr. E. Mojsisovics, whose comributions to the Jahrbuch are both frequent and valuable, gives us a long paper on the Triassic period in the E st Alps. He discusses the distribution of the Triassic fauna, and shows ttut the formation itself may be divided into zones, each characterised by certain well-marked species; further, he describes at length the nature of the deposits, and points out thit the trias is characterised throughout by the constant presence of poorly fossiliferous limestone and dolomite and richly fossiliferous marl and calcareous marl.—The only geological paper in No. 2 is one by Dr. Guido Stache, On the palæozoic regions of the East Alps. The author describes in considerable detail the structure of the rock-masses forming the Alpine lands of Austria, and gives a coloured geological map of the regions described, and two plates of horizontal sections.—Amongst the mineralogical papers accompanying these numbers of the Jahrbuch may be noted one by Dr. Doelter, On the trachyte of the Siebenbürgischen metalliierous mountains, in which a number of analyses are given.—Herr Kalkowsky furnishes an account of the microscopy of the felsite and pechstein of Saxony.—A new mineral (Ludwigite) from Banat is described by Tschermak; and a Report of the volcanic eruptions and earthquakes that took place during last year, is given by C. W. Fuclis. The latter author furnishes a translation from the Swedish of Nauckhoff's paper On the occurrence of native iron in a basalt vein at Ovifak, in Greenland, in connection with which we note also a paper by the editor (Tschermak) On the meteorite-find in Greenland.