The Skiddaw Granite and its Residual Products

Introduction The Skiddaw granite occurs in an area that has long been noted for its interesting and varied assortment of rocks and for the complexity of its geological structure. Jameson's “Mineralogy”, published in 1820, mentions certain minerals as occurring “in granite, near the source of the river Caldew, Cumberland”, while the Sinen Gill and central outcrops of the granite are marked on William Smith's first geological map of the county, which appeared in 1824. No important geological work seems to have been done in this district, however, until 1870, when J. Clifton Ward carried out the first official geological survey. In addition to mapping the area, he contributed a Survey Memoir (Ward, 1876) and also a paper dealing with the granitic rocks of the Lake District (Ward, 1875–76), which includes an account of the Skiddaw granite. At a later date the district received the attention of A. Harker (1894), who published a notable work dealing with the marginal variations of the gabbro of Carrock Fell, and with its associated rocks. A paper which requires special notice in the present discussion, however, is one by the same author which appeared in the following year (Harker, 1895). In this he deals with the greisen of Grainsgill (formerly termed by Ward a “very quartzo-micaceous granite”) and discusses its relationship to the Skiddaw granite. He concluded that this rock represents the mother-liquor extruded from the granite by earth-movements after crystallization had proceeded to some extent in that body. At a still later period the