TRJPFEAN SERIES. 185 



somewhat similar beds are known to occur in places 

 along the coast of Arabia, underlying the nummulitic 

 series, just as the Bombay traps do in Guzerat and 

 Cutch, it is a very interesting question for future in- 

 vestigation, what connexion exists between the various 

 upper secondary or lower tertiary bedded traps of 

 South-western Asia and Eastern Africa ? Should they 

 be proved to have been formerly connected, and to be 

 portions of the same great ancient volcanic region, an 

 idea which seems by no means improbable, their study 

 will become one of very great interest as connected with 

 the geological history of the earth's surface. In every 

 respect the bedded traps are very remarkable, and deserv- 

 ing of far more attention from geologists than they have 

 hitherto received. Nothing resembling them has yet 

 been shown to be in process of formation upon the 

 earth's present surface, and their mode of origin is stiU 

 extremely obscure.^ 



B. MAGDALA GROUP OF TRAPS. 



The higher volcanic beds are distinguished petrolo- 

 gically from the lower mainly by the frequent occurrence 

 of thick beds of trachyte, usually more or less crystal- 

 line, and not unfrequently containing small beautifully- 

 formed glassy crystals of felspar with rounded angles. 



^ I have endeavoured, in a paper on the " Traps of Western India,'' pub- 

 lished in the " Memoirs of the Geological Survey of India,'' vol. vi., to bring 

 together all that is known as yet concerning the bedded traps of that 

 country. A great part of the description is equally applicable to the rocks 

 of Abyssinia. 



