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.

(_a._) _Physical Features._--Abyssinia forms a compact region of lofty
plateaux intersected by deep valleys, interposed between the basin of
the Nile on the west, and the low-lying tract bordering the Red Sea and
the Indian Ocean on the east. The plateaux are deeply intersected by
valleys and ravines, giving birth to streams which feed the head waters
of the Blue Nile (Bahr el Arak) and the Atbara. Several fine lakes lie
in the lap of the mountains, of which the Zana, or Dembia, is the
largest, and next Ashangi, visited by the British army on its march to
Magdala in 1868, and which, from its form and the volcanic nature of the
surrounding hills, appears to occupy the hollow of an extinct crater.
The table-land of Abyssinia reaches its highest elevation along the
eastern and southern margin, where its average height may be 8,000 to
10,000 feet; but some peaks rise to a height of 12,000 to 15,000 feet in
Shoa and Ankobar.[1]

(_b._) _Basaltic Lava Sheets._--An enormous area of this country seems
to be composed of volcanic rocks chiefly in the form of sheets of
basaltic lava, which rise into high plateaux, and break off in
steep--sometimes precipitous--mural escarpments along the sides of the
valleys. These are divisible into the following series:--

(1) _The Ashangi Volcanic Series._--The earliest forerunners of the more
recent lavas seem to have been erupted in Jurassic times, in the form of
sheets of contemporaneous basalt or dolerite amongst the Antola
limestones which are of this p