;8o 



NA TURE 



[January 27, 1910 



striking manner the varied and comprehensive character of 

 ihe work carried on by the U.S. Geological Survey. The 

 first volume constitutes a general review of the surface 

 water supply over a very considerable tract of country, 

 ■comprising the drainage basins of the rivers James, 

 Roanoke, Yadkin or Pedee, Santee, Savannah, Ogeechee, 

 Altamaha, Satello, St. John, Peace, Withlacoochee, 

 Suwanee, Ocklockonee, Apalachicola, Choctawhatchee, 

 Escamba, Mobile, Pascagoula, and Pearl ; while the second 

 is a comparatively local and complete investigation into 

 the wells and springs of Connecticut. 



An introduction to the former volume gives a brief 

 resume of the scope of investigations and the purposes of 

 the work, with a description of the field methods employed 

 for measuring stream flow, from which it appears that 

 the system most generally in use is that of gauging by 

 means of sectional areas and velocity readings. These last 

 are taken by the Price current meter. Fig. i illustrates 

 in a typical manner the plan of operations. At the selected 

 ■station the river bed is divided transversely into any con- 

 venient number of points, at which records are taken both 



of well supply must be through joints and fractures. A 

 study of the occurrence of these joints, accordingly, is of 

 great utility and value, and the data collected cannot fail 

 to prove of more than local interest on account of the 

 scarcity of information on the subject. B> C. 



Fk,. I.— Bridge St, 



of the depth and the velocity. The latter is determined 

 by two observations in each case, at one-fifth and four- 

 fifths of the total depth respectively. The average of 

 these two readings gives the mean velocity of the current 

 very closely for open-water conditions. The discharge is 

 obtained by a simple computation of the cross-sectional 

 area of the strips multiplied by the average of the mean 

 velocities at their ends. 



The second volume contains interesting chapters on the 

 physiography, meteorology, and geology of the State of 

 Connecticut, and not the least valuable feature is the study 

 by Mr. Ellis of the conditions affecting the occurrence of 

 water in crystalline rocks. The term crystalline is taken 

 as covering both igneous (granite, diabase, gabbro, &c.) 

 and metamorphic (schists and gneisses) varieties. More 

 than two-thirds of the area of the State is underlain by 

 rocks of this type, and a large number of wells have been 

 driven into them. It is pointed out that the porosity of 

 crystalline rock is very slight (averaging 0-5 per cent, or 

 less), and that the only circulation of water which has 

 sufficient rapidity of movement to be of value as a source 

 KO. 2100, VOL. S2] 



RECENT WORK OF GEOLOGICAL SURVEYS. 

 I. 



Great Britain and India. 

 'pHE wide range of work done by the Geological Survey 

 of Great Britain is again seen in the " Summary of 

 Progress for 190S " (1909, price is.). The numerous 

 notes made on observations in England, Wales, and Scot- 

 land are, of course, only preliminary to their development 

 in future memoirs ; but we may here direct attention to 

 the careful re-examination of two marine Devonian inter- 

 calations in the Upper Old Red Sandstone near Milford 

 Haven (p. 35), and to the description of the Achanarras 

 beds (Middle Old Red Sandstone) 

 of Caithness, by Mr. R. G. 

 Carruthers (p. S7). Caithness 

 has also yielded a mass of sand- 

 stone with Lower Cretaceous 

 fossils (p. 62). Even if this proves 

 to be transported, like the blocks 

 of chalk in Aber-leenshire, it will 

 remain a remarkable addition to 

 our knowledge of the extent of 

 the early Cretaceous sea. The 

 Petrographical Department has 

 shown the presence of nepheline 

 in several rocks of the Midland 

 Valley of Scotland (p. 44). 



The memoirs published recently 

 include one of economic import- 

 ance on the water-supply of Bed- 

 fordshire and Northamptonshire, 

 with rainfall-maps supplied bv 

 Dr. H. R. Mill (1909, price 

 4s. 6d.). Dr. Strahan has written 

 a second edition of the memoir on 

 the country around Newport, in 

 the South Wales coalfield (igog, 

 price IS. 6d.), which shows how 

 knowledge advances, even during 

 a decade. An interesting break 

 near the top of the Carboniferous 

 Limestone is pointed out, and the 

 Old Red Sandstone is now divided 

 into an upper and a lower series. 

 It is probably not generally known 

 that the characteristic Upper Old 

 Red Sandstone mollusc, Arch- 

 anodon jukesii, was found near 

 Talgarth in 1895, the specimens 

 being now in the British Museum. 

 .\ terse and effective account is 

 given on p. 89 of the passage from the continental beds of 

 the Trias in this district through the Rhaetic shales to the 

 marine Jurassic system, and a comparison is made between 

 this complete sequence and that observable where the 

 Cretaceous sea spread across the Weald. 



The description of the geology of the country around 

 Basingstoke (1909, price 2s.), accompanying the colour- 

 printed Sheet 284 (_is. 6d.), has been entrusted to Mr. 

 H. J. Osborne White. The area is a familiar one, at the 

 junction of the London Basin and the great swelling rolls 

 of Salisbury Plain. The chalk district was formerly 

 strewn with sarsens, which have been traced to a sand- 

 stone in the Reading beds. The Plateau Gravels raise 

 interesting questions of former river-courses, end it appears 

 that the Wey basin (p. 90) has now captured waters 

 that once brought Lower Greensand debris westward into 

 the valley of the Loddon. The soft Eocene strata are 

 responsible for considerable " mutability of the lines of 

 drainage." 



The memoir on the country around Bodmin and St. 

 .Austell, by Messrs. Ussher, Barrow, and MacAlister (1909, 



