510 Geological Society. 



Hog's Back. From this pond a small stream flows towards Run- 

 fold, and passing thence across the depressed chalk, continues its 

 course to the county stream, or Blackwater river, receiving appa- 

 rently a small augmentation from a spring at Andrew's hop-kiln. 

 This gap in the chalk at Runfold, not having been hitherto noticed 

 by geologists, Mr. Long conceives, that it deserves to be recorded 

 among the apertures of the North Downs. 



An extract was last read from a letter addressed to Mr. Lyell by 

 Capt. Charters, F.G.S., and dated Cape Town, Nov. 12, 1838. 



During an extensive tour through the colony, Capt. Charters's 

 attention was drawn to a vast deposit of greenstone, overlying the 

 horizontally stratified sandstone which occupies so large a portion of 

 Southern Africa. The following localities are mentioned in the letter. 

 A hill close to Fort Beaufort, on the Kaffir frontier. The banks of the 

 Great Fish River, near the small town of Cradock, in the neighbour- 

 hood of wliich quantities of spherical masses of trap are heaped to- 

 gether, the surrounding sandstone mountains being of considerable 

 elevation, and having their flanks and sometimes their tops very fre- 

 quently covered with loose fragments of trap. On the right bank of 

 the river and about a mile from the town, is exhibited a section, 

 consisting in the lowest part of inclined strata of clay slate, in the 

 middle of horizontal beds of sandstone, and in the uppermost of 

 masses of trap. The same geological structure prevails in passing 

 through the Tanka district, behind the Winterberg range to Shiloh, 

 and thence to Colesberg, near the Orange river. From Colesberg, 

 Captain Charters proceeded to Graf Keyuet by the Schneeberg, and 

 he found that the only variation in the nature of the country consisted 

 in a considerable diminution of the quantity of greenstone. The left 

 of a narrow gorge through which the Sunday river passes, presents 

 an abrupt precipice 300 feet high and as many yards long, composed 

 of columnar greenstone resting at its foot on horizontal strata of 

 sandstone. 



March 13. — A paper on the geology of the North Western part of 

 Asia Minor, from the peninsula of Cyzicus, on the coast of the sea 

 of Marmara, to Koola, with a description of the Katakekaumene, by 

 William John Hamilton, Esq., Sec. G.S., was read. 



The memoir is divided into two parts, the first containing an ac- 

 count of the country between Cyzicus and Koola, the second a 

 description of the Katakekaumene. 



The line of route taken by Mr. Hamilton from Cyzicus, ascends 

 the valley of the Macestus to the sources of that river near Simaul, 

 then crosses the Demirji chain, and afterwards passes through Kars- 

 kieui and Selendi to Koola, in the Katakekaumene, the whole distance 

 being about 170 miles. The principal leading feature of the district 

 is the Demirji chain reaching from Pergamum on the west, to the lofty 

 mountain of the Ak Dagh or Shapkhana Dagh on the east, and it is 

 prolonged in that direction by a loft)' range which extends E.S.E. 

 to Morad Dagh, south of Kutahiyah, and thence byAioniKarahissar to 

 Sultan Dagh, an extension of one of the chains of Mount Taurus, 

 so that the Demirji range forms a portion of the central axis of Asia 



