- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
"During the Archaean times a volcanic geanticlinal arc, now represented by the Dalma lavas, tuffs and agglomerates extended roughly east-west for more than 150 miles. The geosynclinal trough in the southern, concave side of the arc was filled with argillaceous sediments, thin subgraywackes and orthoquartzites derived from a land mass to the south. The trough in the northern, convex side of the arc was filled with a huge thickness of argillaceous sediments associated with graywackes, siliceous limestones, sandstones and preorogenic ultrabasic and basic intrusives. Both the troughs near their border with the volcanic arc were filled with pyroclastic materials."