514 Reviews— Geological Survey Memoirs— 
Often they have no outlet, and then the water can only be lost by 
evaporation. They are full to overflowing when the seasonal rains 
fall, but during the long drought the waters gradually diminish, and 
in many instances totally disappear. 
The water which finds its way into these pools or lakes brings with 
it matter in suspension and in solution. The former settles at the 
bottom as a fine mud. The mud, on drying, shrinks and forms 
the triradiate cracks characteristic of contracting sheets ; it receives 
the imprints of animals’ feet when they come to drink, and the 
impressions of rain when it falls. 
The mud from the margin of a partially dried up vley at Riverton 
in South Africa shows all these features, and in addition it contains 
vast quantities of the carapaces of Hstheria, a tiny Crustacean which 
has its proper habitat in such surroundings.! 
The matter brought into the pools in solution will tend to 
concentrate as the water diminishes, and on complete drying, deposits 
of salt, gypsum and other salts will be left behind. 
The salinity of the water will vary with the season. Thus, pools 
in the Rajputana desert in India are fresh for two or three months 
in the year. One constantly comes across contradictory statements in 
reading books of travel as to the salinity or otherwise of certain 
lakes. The observations may be right in each case if the travellers 
visited the lakes at different seasons of the year. 
(To be concluded in our next Number.) 
RHVIT HWS. 
Memores oF THE GEOLOGICAL SURVEY. 
J.—Tue Gerotocy or tHE Souta Wats Coarrierp. Part VII: Tu 
Country arounD AmManrorD. By Dr. A. Srrawan, F.R.S., 
T. C. Canrritt, B.Sc., E. E. L. Drxon, B.Sc., and H. H. Tomas, 
B.Sc. Text, pp. 246, with 12 illustrations, price 2s. 6d. Colour- 
printed maps, Sheet 230, Drift and Solid, 1s. 6d. each. 
Part VIII: Tue Country arounp Swansea. By Dr. A. 
Srrawan, with parts by R. H. Trppeman, M.A., Dr. W. Gizsson, 
and K. E. L. Dixon, B.Sc. Text, pp. 170, with 4 illustrations 
and 5 plates, price 2s. 6d. Colour-printed maps, Sheet 247, 
Drift and Solid, 1s. 6d. each. 
ITH the publication of these Memoirs and that of Part IX 
(West Gower) already noticed in the Gxonoetcat Magazine 
(August, 1907, p. 871) we witness the completion of the survey of 
the main portions of the great South Wales Coalfield, and Dr. Strahan 
is to be congratulated on the progress thus made in a task in which 
he has taken the prominent part and has personally superintended. 
1 «Habitat of Estheria’’: Trias Report, British Association, 1905; and Monog. 
Pal. Soc., 1862, p. 57. 
