GEOLOGY, 307 



ON THE FORMER EXISTENCE OF A GREAT SEA IN THE INTERIOR 



OF RUSSIA. 



There is perhaps no feature of more commanding interest, in its bearing 

 on the physical outlines of the earth at a period which approaches near 

 to our own era, than the fact, which geological researches have established, 

 that there has existed a vast interior sea, which covered all the area be- 

 tween Constantinople on the west and Turkestan on the east, or a length of 

 nearly 2,000 miles, whilst it ranged irregularly from north to south over a 

 space broader than the present Caspian Sea is long, or of about 1,000 miles. 

 Of this great submerged area, the Seas of Azof, the Caspian, and the Aral, 

 are now clearly the chief detached remnants. For the very same species 

 of mollusca which are now living in these seas are found in a fossil state 

 in limestones forming cliffs on their shores, or on those of the Black Sea, 

 or in masses of intermediate land, which are simply elevated bottoms of 

 a once continuous vast internal sea, the whole of whose inhabitants were 

 as distinct from those of the then ocean 'as are the present inhabitants of 

 these detached Caspians from those of the present Mediterranean and 

 ocean. &V R> ! Murchisons Address to the Royal Geoff. Soc. 



ON THE STRUCTURE OF LUNAR VOLCANIC CRATERS. 



Mr. James Nasmyth, at the British Association, presented a communica- 

 tion on the above subject, which was illustrated by a model of the lunar 

 volcano Copernicus and a diagram of Simpelius ; each of which consists 

 of a plateau, with a small central cone, surrounded by a ring-shaped ele- 

 vation, exhibiting concentric ridges or terraces. The circular elevations 

 were supposed to have been formed by the accumulation of materials 

 erupted with great energy to various distances, according to the intensity 

 of tKe force ; giving rise to concentric ridgep, or terraces of deposition, 

 which are often nearly entire circles, one within the other. Besides these 

 there are other terraces, forming only segments of circles, within the prin- 

 cipal rings, which were attributed to the agency of landslips ; these in most 

 instances correspond to notches in the edge of the crater, from which they 

 have slipped, and their debris has rolled onward over the plateau, towards 

 the centre. The central cone was attributed to the last expiring efforts of 

 the eruptive action. 



Prof. Phillips observed that, although there might be no sign of the 

 existence of water on the present surface of the moon, he thought there 

 were many indications of former aqueous action. There were elevations 

 like the escars of S \veden and Ireland, and small gullies converging into larger, 

 like the channels of mountain streams. He also called attention to the 

 narrow, dark lines, many miles in length, occasioned by shadows which 

 change with the direction of the sunlight, showing that the level is higher 

 on one side than the other, as in cases of fault. 



