who is ready to face such issues, rejoice also to know that he is not the only one who sees the tremendous importance of them even in America at the present day. GEOGRAPHICAL NOTES. EUROPE. The Rhone Delta in Historic Times. Mr. R. D. Oldham contributes to the issues of Nature 1 for July 4, 11, and 18 last a series of articles, illustrated by sketch-maps, on the changes which have taken place in the Rhone Delta since Roman times. His study is based upon a correlation of geological and historical evidence, and leads him to the conclusion that in the eighth and ninth centuries a subsidence of the land took place, to the extent of about fifteen feet. In Roman times the extent and outline of the delta seem to have been approximately the same as at present, but owing to the higher level at which the land stood, the existing extensive salt lakes and marshes were then dry land, and the now desolate Camargue was a fertile, populous, and prosperous region. Along the sea-coast there were probably lagoons, separated from the sea by a barrier made up of sand dunes and a sandy beach, which swept round the coast in even curves. The mouth of the river then lay to the west of the present mouth, and at it there was an alluvial projection, exactly analogous to that which has been built up along the present channel. When the subsidence occurred in post-Roman times, the low-level deposits along the coast and at the mouth of the river were plunged beneath the sea, and a large part of the higher ground behind them was also brought below sea-level. As a result the original mature coast-line disappeared, and was replaced by an archipelago, the river ending far inland in a land-locked inlet of shallow water. After subsidence had ceased the river was occupied, during a period of some eight centuries, in filling up the submerged areas of its delta, and in pushing forward its mouth. By about the middle of the seventeenth century it again. reached the sea-front, and a century and a half later the continuous barrier and beach, with the curved outline of maturity, had again been established. The result was that along the sea-coast the delta had resumed the general type and approximately the outline of earlier times. In the interior, however, large areas of what was then dry land are still occupied by salt water lakes and marshes, having been protected, by accidents of surface configuration, from river deposits, so that they still remain much as they were left at the close of the period of subsidence. 1 See also the Geographical Journal for May 1925. ASIA. Makalla, South Arabia.—A substantial pamphlet by Mr. O. H. Little, published by the Survey of Egypt, Geological Survey, gives a detailed account of a topographical and geological survey of an area round Makalla in South Arabia, undertaken in the winter of 1919-20. The report, entitled "The Geography and Geology of Makalla," appeared this year. The investigations were undertaken by request of the Sultan of Shehr and Makalla, who wished to have some occurrences of lignite and oil-shale examined in detail. No maps of the country were in existence, and Mr. Little endeavoured to make as complete a survey as the conditions permitted. His report is accompanied by a geological map. So far as the immediate object is concerned, it was shown that considerable amounts of lignite exist, which should be of great value in a fuel-less country like South Arabia. Unfortunately, however, the deposits so far discovered are for the most part very inaccessible, and it seems doubtful if they could be worked at a profit, in view especially of the difficulty of transport. Oil-shales also occur, but those at present known are not of good quality, and elsewhere the hostility of the tribesmen is a great obstacle to prospecting. But the most generally interesting fact which emerged from the survey was the discovery of what seems to be a permanent river, which enters the sea between Ras el Kalb and Ras Rigaima, south-east of Makalla, forming a delta which is an important agricultural district. The river is apparently over 200 kilometres long, and has villages along its banks wherever the land can be cultivated. The delta forms the district of Meifa, and Mr. Little's map showed the area under cultivation to reach 2970 acres. Though there had been no heavy rain for five years the average discharge of the river was estimated at one cubic metre per second, but it varies greatly from point to point. The water, though slightly saline, was quite drinkable. In addition to this permanent stream there was running water at the heads of practically all the wadis visited, this water being used for irrigation purposes. Owing, however, to the small amount of land which can be cultivated, the country is not self-supporting, and some food has to be imported. AFRICA. The Mid-Atlas of Morocco.-In La Géographie for March last Dr. Russo discusses some points in regard to the structure and relief of Morocco, with special reference to the region called Moyen Atlas by Ritter, which lies between the High Atlas and the Rif (Little Atlas). He comes to the conclusion that the Mid-Atlas is not a mountain chain, but a complex of independent chains traversing a plateau region continuous with the High Plateau of Algeria. The southern chain of the Mid-Atlas belongs, like the High Atlas of Morocco, to the Saharan Atlas of Algeria, but the northern and central sections form a part of the accessory folds of the same system. Irrigation in South Africa. To the Geographical Journal for April last Mr. C. Daryll Forde contributes an article on this subject, illustrated by sketch-maps, which brings out the generally unfavourable conditions, so far as agriculture is concerned, which prevail throughout the Union. It is stated that it is only in the hinterland of the eastern coast between the Drakensberg and the sea that irrigation is unnecessary for the majority of crops; throughout almost the whole of the rest of the Union it is required. In parts, as over most of the Karoo and in the southwest of the Orange Free State, this is due to the small total rainfall, the high evaporation, the uncertainty of the fall and the tendency for it to occur chiefly in local, light showers, often evaporated almost at once. All the common summer field crops require an assured annual fall of 24 inches, and fodder crops one of 15 inches to be successful without irrigation, and in the areas named the average annual fall is below the latter figure. But the mean annual fall is only a rough guide to the need of irrigation; the time of fall, the reliability, the run-off and so forth are of great importance. Unfortunately, except for the south-west corner of the Cape Province the whole of South Africa receives the greater part of its rainfall in summer, and the limitation to the hotter season increases in the direction from south-west to north-east until in the Transvaal 90 per cent. of the rain falls in the six hotter months. Further, except in the extreme east, precipitation is scanty and unreliable in the spring when water is required by winter crops to complete their growth and by summer crops to start it. Summer conditions of temperature tend to set in with great suddenness in August and September, when dry parching winds prevail. In the absence of irrigation, agricultural operations even in areas with a fair total fall are delayed by this spring drought, with a resultant limitation of the growing season, for in, e.g., parts of the Transvaal, frost may check growth in autumn. It is estimated that about 90 per cent. of the total area of the Union requires irrigation water in spring, while in winter no irrigation is really necessary. The next difficulty which arises is that only the very best lands will repay the cost of irrigation works, and such lands are not widespread in South Africa. Of the total area of nearly half a million square miles it is estimated that less than ten thousand square miles, or about six million acres, consists of land good enough for profitable irrigation, and only about four million acres can actually be irrigated. The first great impetus to irrigation works came towards the end of last century, when the rapid rise of ostrich-farming led to much land being planted with lucerne. Since the collapse of the ostrich-feather industry lucerne is used as a fodder crop for all purposes, and is exported to England and Holland. Any further extensive development of irrigation must be linked with the development of the stock industry, lucerne with root crops and oats being grown as supplements to the natural pasture. In the Breede River basin irrigation is used for all forms of fruit-farming, the vine being grown under irrigation. But except in this area vine-growing under irrigation is little practised. In the Transvaal tobacco is grown as an irrigation crop. Irrigation is also necessary for citrus-growing. The orange takes about nine months to mature, so that even in areas where the summer rains are good, water, of which the trees require large amounts, must be supplied in spring and autumn. Citrus-growing is important throughout the coast zone in Cape Colony, in the upper Sunday valley round Graaf Reinet, and in central and northern Transvaal. Tobacco, citrus, and other fruits can, however, only be grown in areas with good rail connections, and fodder crops, as stated, must remain the chief object of irrigation agriculture. motor-cars. AMERICA. Motor Traffic and Wild Life in U.S.A.-Prof. Dayton Stoner, of the University of Iowa, made, during June and July 1924, some curious observations on a short motor tour in that State, of which he gives a summary account in Science for January 16 last. He made a journey from Iowa City to Iowa Lakeside Laboratory, on West Lake Okoboji, a distance of 316 miles, and back, and took a careful census of the dead animals encountered en route, all apparently killed by passing The route was through typical Iowa farming communities, mostly fairly well-populated, and of varied physiographical type, prairie, wood, and marshland all being represented. About 200 miles of the road was surfaced with gravel, the remainder was a dirt" road, and it was noted that the number of dead animals was greater on the surfaced portion, where greater speed is possible. The total number of dead animals noted was 225, belonging to 29 species, and including mammals, birds, and reptiles. All the animals counted had been recently killed, and with the exception of 3 cats and 26 fowls no domesticated animals were represented, though no comment is made on this fact. The form most numerously represented was the redheaded woodpecker, of which bird no less than 53 specimens were counted. This bird tends to feed on roads, and rises somewhat slowly; but Professor Stoner is of opinion that a speed of 35-40 miles per hour is necessary to overrun the birds. If the conditions described are at all typical throughout Iowa State and the United States generally, then, as he points out, the motor-car must be regarded as one of the important checks to the natural increase of many forms of wild life. ECONOMIC GEOGRAPHY. The Power Resources of Australia and New Guinea. The Institution of Engineers, Australia, compiled, for the World Power Conference held at London in 1924, a somewhat voluminous Report on this subject, a copy of which has been sent to us. The subjects dealt with include water-power, coal resources and liquid fuels, as well as a discussion of existing power supplies in Australia and New Guinea. VOL. XLI. U There are a number of illustrations, including a striking view of the reservoir at Barren Jack, New South Wales, and several maps. It is noted that so far as water-power is concerned the greatest potentialities exist in Tasmania and in Papua. The resources of Tasmania are estimated at about three-quarters of a million horse power, of which not more than 10 per cent. is developed. The resources both of Papua and mandated New Guinea are believed to be great, but as yet there has been scarcely even a preliminary survey. In Australia the possibilities are of course limited to the eastern portion of the continent, but since there water-power and coal resources occur near together, and can be worked in conjunction, the value of the water-power is thereby increased. The water-power cannot, however, be regarded as of great importance, for it is estimated that the total power available from the east coast rivers and from irrigation schemes on the western slopes and plains is approximately equal to that of Tasmania. No very great developments have as yet taken place in Australia, but in Tasmania, where there is a State monopoly for the bulk sale of hydro-electricity, greater advances have been made. It is interesting to note that one of the advantages of hydroelectric developments expressly mentioned is that since only a very small staff is required to operate the plant, "the supply of power is practically free from labour troubles. This advantage is of very great importance, and probably will be of even greater importance in the future." Australia's greatest power resources are of course found in her rich coal-beds, lying often near great centres of population. Petroleum has not yet been found within the country, and only small amounts of shaleoils and tar-oils are locally produced. NEW BOOKS. EUROPE. Venice on Foot. By HUGH A. DOUGLAS. London: Methuen and Co., Ltd., 1925. Price 12s. 6d. Many visitors to Venice are under the impression that the gondola and the steamer constitute the only means of communication, and that walking is impossible. Mr. Douglas, with the aid of sketch-maps and detailed descriptions, shows them the error of their ways, and at the same time gives much information not obtainable from the ordinary guide-book. His book was originally published in 1907, and this new and revised edition will prove a true friend to those with the time and the inclination to make a detailed study of the capital of the great mediaval republic. Das Hellenische Thessalien: Landeskundliche und Geschichtliche Beschreibung Thessaliens in der Hellenischen und Römischen Zeit. Von Dr. FRIEDRICH STAHLIN. Stuttgart: J. Engelhorn's Nachf., 1924. The author of this book paid his first visit to Thessaly so long ago as 1904. A second journey was undertaken in 1912, with the help of a grant from the Bavarian Academy of Science. At the end of that year a prize was awarded |