Every transition can be found between perfectly normal ophitic dolerites and typical hornblende-schists, and occasionally the same dike or sill will provide specimens of all the connecting stages.
28 The granites and dolerites from Magan were too fine and too expensive to build with.
The Karroo formation and associate dolerites (Loalemandelstein) occur in the same region.
It occurs in a series of amygdaloidal dolerites or diabases, and in the associated sandstones and conglomerates.
The lower (Ashangi group) consists of basalts and dolerites often amygdaloidal.
While upheavals having a north-eastern strike continued to take place after the Carboniferous epoch,' another series of upheavals, having a north-western strike, and occasioned by the expansion of diabases, dolerites, melaphyres and andesites, occurred later, subsequently at least to the close of the Tertiary period, if not also before it, dislocating former chains and raising rocks to the highest levels by the addition of new upheavals to the older ones.
The axis along which they have been elevated runs north-east and south-west, and on either flank a series of " green rocks " appears, consisting of altered amygdaloidal andesitic lavas, intrusive dolerites, coarse gabbros and diorites, and at Beagh-beg and Creggan in central Tyrone ancient rhyolitic tuffs.