(_c._) _Geological Age._--As regards the geological age of this great volcanic series much uncertainty exists, owing to the absence of marine forms in the inter-trappean beds. One single species, _Cardita variabilis_, has been observed as occurring in these beds, and in the limestone below the base of the trap at Dudukur. The _facies_ of the forms in this limestone is Tertiary; but there is a remarkable absence of characteristic genera. On the other hand, Mr. Blanford states that the bedded traps are seen to underlie the Eocene Tertiary strata with _Nummulites_ in Guzerat and Cutch,[2] which would appear to determine the limit of their age in one direction. On balancing the evidence, however, it is tolerably clear that the volcanic eruptions commenced towards the close of the Cretaceous period, and continued into the commencement of the Tertiary, thus bridging over the interval between the two epochs; and since the greater sheets have been exposed throughout the whole of the Tertiary and Quarternary periods, it is not surprising if they have suffered enormously from denuding agencies, and that any craters or cones of eruption that may once have existed have disappeared. [1] The Deccan Traps have been described by Sykes, _Geol. Trans._, 2nd Series, vol. iv.; also Rev. S. Hislop, "On the Geology of the Neighbourhood of Nagpur, Central India," _Quart. Journ. Geol. Soc._, vol. x. p. 274; and _Ibid._, vol. xvi. p. 154. Also, H. B. Medlicott and W. T. Blanford, _Manual of the Geology of India_, vol. i. (1879). [2] Blanford, _Geology of Abyssinia_, p. 185. CHAPTER II. ABYSSINIAN TABLE-LANDS. Another region in which the volcanic phenomena bear a remarkable analogy to those of Central India, just described, is that of Abyssinia. Nor are these tracts so widely separated that they may not be considered as portions of one great volcanic area extending from Abyssinia, through Southern Arabia, into Cutch and the Deccan, in the one direction, while the great volcanic cones of Kenia and Kilimanjaro, with their surrounding tracts of volcanic matter, may be the extreme prolongations in the other. Along this tract volcanic operations are still active in the Gulf of Aden; and cones quite unchanged in form, and evidently of very recent date, abound in many places along the coast both of Arabia and Africa. The volcanic formations of this tract are, however, much more recent than those which occupy the high plateaux of Central and Southern Abyssinia of which we are about to speak.