Correspondence — Br. T. Eterry Hunt. 573 



material remaining partly in the position in which the ice left it, 

 and partly lifted by the bergs which became detached from the ice. 

 Such part of it as was lifted was dropped over the sea-bottom at no 

 great distance from its point of extrusion, and in that way the 

 marine shells occurring in a seam of sand in the midst of this clay at 

 Dimlington and Bridlington on the Yorkshire coast became im- 

 bedded, the mollusca which, had established themselves on the 

 surface of this moraine material having been thus smothered under 

 a lifted mass of the same, which was dropped from a berg. The 

 authors point out that precisely in the same way in which the 

 Middle Glacial is found stretching out southwards and eastwards 

 beyond the Upper Glacial Clay in Suffolk and in Herts, and is 

 succeeded by such clay both vertically and horizontally, so does the 

 earlier formed part of the Upper Glacial Clay, or that with chalk 

 debris, stretch southwards beyond the later formed part, or that desti- 

 tute of such debris, and is succeeded by it, both vertically and horizon- 

 tally. This, they consider, shows that the Middle and Upper 

 Glacial deposits, which constitute an unbroken succession, were due 

 to the gradually receding position of the land-ice during their 

 accumulation, the sequence being terminated with the Moel Tryfaen 

 and Macclesfield gravels, which were accumulated during the dis- 

 connexion and gradual disappearance of the ice, and while the land 

 still continued deeply submerged. 



coiRi^iEsiPOisrnDiBn^ciH]. 



INTERNATIONAL GEOLOGICAL CONGRESS. 



Sir, — Tlie activity which has prevailed in the study of geology within the past 

 generation has given to it a great importance both in a scientific and an economic 

 point of view, and has resulted in a large accumulation of facts and materials. 

 Workers m different countries have however pursued their labours to a great extent 

 independently of each other, and have given their results in such ways that it is often 

 difficult to co-ordinate them. Those geologists from Europe and Ajiierica who have 

 been at the International Exhibition at Philadelphia in 1876, have found there 

 important collections of geological maps and sections, with rocks and organic remains 

 from various regions of North and South America, as well as from many countries 

 of Europe, and they have become deeply impressed with the great advantages to be 

 gained by their comparative study. It was moreover evident that the bringing to- 

 gether of a still larger number of such collections in accordance with a previously 

 arranged plan, could not fail to lead to important results for geological science. The 

 International Exhibition to be held at Paris in 1878 will fui-nish such an occasion, 

 and it is proposed to invite to that end governmental geological surveys, learned 

 societies and private individuals throughout the world, to send to Paris such collections 

 as will make the geological department of that exhibition as comjjlete as possible. 



In order to take advantage of the collections which may thus be brought together, 

 it is moreover proposed to convoke an International Geological Congress, to be held 

 at Paris at some time during the Exhibition of 187S, and to make that Congress an 

 occasion for considering many disputed problems in Geology. 



In accordance with this plan it is proposed that the Geological Department of the 

 International Exhibition of 1878 shall embrace : 



I. Collections of crystalline rocks, both crystalline schists and massive or eruptive 

 rocks, including the so-called contact-formations and the residts of the local 

 alteration of imcrystalline sediments by eruptive masses. In this connexion 

 are to be desired all examples of organic remains found in crystalline rocks, 

 including Eozoou and related forms. These collections should moreover comprehend 



