458 



NATURE 



[June io, 1920 



made from them we may observe other features 

 of research interest. The story of the earth 

 movements in the Jordan rift is not yet clear, 

 while there has been much discussion about the 

 climate of the region during recent and prehistoric 

 times. In some of the photographs taken, we 

 have good evidence of very recent faulting, and 

 we may distinguish a fault scarp in the lake-beds 

 (Late Tertiary). We find that the trough faulting 

 has resulted in the incision of many of the tribu- 

 tary streams, and in several places in canon forma- 

 tion. When we look at the drainage system from 

 the point of view of climatic change we find evi- 

 dence of a former period of abundant precipita- 

 tion, during which much of the present surface 

 sculpture of the Judaean hills was effected ; but 

 this period was a remote one, and preceded the 

 drying up of the Jordan lake to give the present 

 valley. Passing up to the north of Palestine, we 

 have good evidence from a dry gorge, terraced 

 valleys and drainage forms, that at a former 

 period the River Jordan originated in Central 

 Syria; but afterwards the Syrian portion 

 of the river was captured by the Litani. 

 This capture was largely the result of a general 

 uplift of the country, and several of the oblique 

 air views of the coastal plain of Palestine, espe- 

 cially near Mount Carmel, show very well the 

 plain of marine denudation stretching from the 

 present shore to the foot of the hills. 



It is in the portrayal of the geographical 

 features in the most complete and detailed 

 fashion, so that their developmental story can be 

 studied and deciphered, that aeroplane photo- 

 graphy excels. If the whole of the Palestine 

 material could be carefully studied by the physical 

 geologist, a great deal of information would 

 result, for the above-mentioned deductions have 

 been made from the study of a few small sets of 

 photographs which had been chosen at random 

 for other purposes. 



The investigator of solid geology has naturally 

 little to learn from photographs, but in some 

 places, where the climate is arid and the ground 

 almost devoid of soil, the boundaries of some 

 of the harder beds may become visible, while in 

 other cases the bedding is clearly seen, and the 

 underlying structure may be brought out by 

 surface weathering. A photograph taken during 

 the first flight ever made from Egypt to India 

 showed an interesting locality in western Persia, 

 where a well-marked anticline had been laid bare 

 by surface erosion. 



Botany. — The student of vegetation who may 

 be sufficiently fortunate to obtain aerial photo- 

 graphs of the ground is at once in possession of 

 the basis of an ideal vegetation map. Diff"erent 

 types of vegetation show up very clearly, and also, 

 of course, the transition from desert to open and 

 closed plant associations (see Fig. 2). It is naturally 

 necessary to go over the ground with the photo- 

 graphs, but after a short time the characteristic 

 tones and appearance of different vegetation types 

 can be readily picked out. Even among crops 

 it is possible to distinguish barley, wheat, and 

 NO. 2641, VOL. 105I 



maize, besides other plants, like cotton, which 

 have a distinct habit and growth period. Prac- 

 tical use of these facts was made in Mesopotamia 

 for ascertaining the acreage under wheat cultiva- 

 tion, and trials have been made in India with the 

 view of carrying out crop-surveys by aeroplane 

 photography. 



I have not had the opportunity of making many 

 observations on this subject, but it may be of 

 interest to mention a small point observed in 

 connection with the distribution of the willow and 

 tamarisk scrub of the Jordan valley. This vegeta- 

 tion is limited by the water supply from the river, 

 and succeeds in following the stream right down to 

 the Dead Sea. Here, at the mouth of the Jordan, 

 although surrounded by salt lagoons, a narrow 

 belt of vegetation manages to survive as a fringe 

 to the river with its rapidly flowing stream of 

 fresh water. 



Archaeology. ^The utility of aerial photographv 

 to the archaeologist was strikingly illustrated in 



Fig. 2. — Photograph showing the distribution of vegetation in the Sinai 

 desert. The partial colonisation of sand-hills by dwart scrub vegetation 

 — the black spots — is well shown, also some small groups of date palms.- 



I the case of the ninth-century city of Samarra,^ 

 i in Mesopotamia, where views taken from above 

 the apparently formless heaps of earth and 

 rubble give the outlines and plan of streets 

 and buildings. It may be only rarely that similar 

 cases may arise, but experience shows that if 

 I ruins or remains exist in any regular form, their 

 arrangement will be well depicted by the aero- 

 plane camera. We may by this means be able 

 to locate interesting sites which have been more 

 j or less obscured by superimposed material. A 

 feature which was brought to light in Palestine 

 as the result of air survey was the ancient irriga- 

 '. tion system in the south-eastern part of the Jordan 

 valley. An extensive series of old connected 

 ; channels, now filled with scrub vegetation, was 

 j seen ; this must be a relic of the days when the 

 I Jordan valley was under general cultivation, 



[ 2 See Lt.-Col. G. A. Beazley, Geographical Journal, vol. liii., p. ^30, 

 1919- 



