Scientific Intelligence — Geology. 181 



quite impossible not to perceive that the erratic deposit had been 

 formed in the bosom of the sea at a period when glaciers of great 

 size existed on the great islands and peninsulas formed by the chains 

 of the South American mountains. In support of his opinion, M. 

 Grange observed, that, in the present day, a considerable erratic de- 

 posit is now forming in South America, in the same circumstances, 

 and by the same agents, as in the anterior epoch ; the extent and 

 power of the agents alone being diminished. — {JJ' Institute No. 772, 

 p. 318.) 



2. The probable cause of Goitre and Cretinism. — A memoir 

 which M. Grange presented at the same meeting, contains the 

 results of numerous analyses of waters from the talcose, anthraxi- 

 ferous, and cretaceous formations of the Valley of the Isere. 

 These analyses have led the author to some interesting results on 

 the relative quantity of the chlorures, sulphates, and carbonates, 

 found in the waters of different geological periods, and at different 

 heights. Among others, he has made the observation, that the wa- 

 ters of all the villages and valleys in which goitre and cretinism are 

 endemic, contain a considerable quantity of the salts of magnesia, 

 from whatsoever formations the waters flow. We shall give a few 

 details. 



The investigation was made among the mountains which inclose 

 the great Valley of the Isere, mountains which belong, some of them 

 to the system of the Western Alps, attaining the height of 3000 

 metres ; others to the cretaceous and neocomian formations, whose 

 elevation is much less considerable. The author's object in under- 

 taking the task, under the direction of M. Dumas, was to find out 

 the relative quantity of chlorures, sulphates, and carbonates, con- 

 tained in the waters, from the glaciers down to the plain, and to 

 compare the salts dissolved in the waters of the granitoidal or 

 talcose formation with those of the anthraxiferous and cretaceous 

 formations, with a view to determine their absolute and relative 

 quantities. 



The analyses have been made, generally, on 20 litres, and the re- 

 sults referred to 1 litre ; so that the numbers express the absolute 

 weight of the salt and a fraction of a kilogramme of the water ana- 

 lysed. ^ 



The \mters of the glacier of Glezin, obtained in the glacier itself, 

 at a height of 2259 metres, contain carbonic acid, oxygen, and azote 

 in solution, like all running waters, taking into account the small 

 pressure to which they are subjected. The evaporation of these 

 waters gave a small quantity of salts, in which chlorures and sul- 

 phates predominate. 



A comparative examination of the tables of analyses accompany- 

 ing the Memoir, shews, ls«. That the quantity of dissolved salts 

 goes on increasing from the summit of the mountains towards the 

 plain ; 2(i, That in the talcose and anthraxiferous formations, the 



