Lawrence Jameson was a staff-surgeon at the Cape by 1828 and collected rocks and minerals at the places where he was stationed. He resided in Grahamstown from about 1838. In 1839 he published the first geological account of the Eastern Cape, under the title "A few general remarks on the geology of Grahams's Town and its vicinity". His remarks were published in the Grahamstown Journal in three installments, on 3, 24 and 31 January. In part his views were speculative, but he dealt at some length with matters that were important to the local settler community, such as the availability of ground water, the suitability of soil types for agriculture, and the materials available for brick making. He appears to have been aquainted with the views of the German neptunist A.G. Werner, and the German mineralogist J.F.L. Hausmann*. Some of his observations were accurate but others, including that of an enormous trilobite in the local clay slate, were spurious.
Jameson has been credited with discovering the first Karoo fossil reptiles. He mentions finding "a variety of fossil reptiles" in the clay slate of the Grahamstown region, as well as fossilised wood in a greywacke.
His paper created much interest among the settlers in local rocks and minerals, and caused a heated debate on the relative merits of geology and religion as explanations of the world. A.G. Bain* later recalled that he had found Gregory's articles "disjointed and obscure". Gregory left the Cape soon afterwards because of poor health. No other publications by him are known.