The Tertiary Volcanic Rocks of the District of Mozambique

Abstract

Introduction. I. History Of Exploration The Portuguese East-African District of Mozambique was, until recently, one of the least known of the East-African coastlands. Livingstone explored the regions on the south-west (1865) and north (1874), but Mozambique itself he did not touch. Sadebeck (1879) was the first to give a geological description of the sedimentary rocks that fringe the coastal plain of the mainland north and south of Mozambique Island. This work was followed up by Choffat (1903) in an important palæontological memoir on the Cretaceous formations of Conducia Bay. Exploration beyond the coastal zone was initiated by Lieut. H. E. O'Neill, who made a number of successful journeys westwards across the mainland during the years 1881–1884. In his papers (1882, 1884, 1885) he gives a very complete and faithful account of the natives and their customs; but, beyond the suggestion that the prevailing rocks are gneisses and granites, he makes no reference to the geology of the territory. In 1887, Mr. J. T. Last made a journey from Blantyre to the Namuli Peaks, which had for long been considered to be of volcanic origin. This view he disproved (Last, 1887), describing the summit as ‘an almost perpendicular mass of white stone.’ I have since learned from Mr. Last that he referred in this expression to the grey granite and gneiss which builds up the Namuli Peaks, as it does the other mountainous masses of the country. Thus, until a few years ago, Mozambique, with the exception of part of the