III.—The Igneous Rocks, etc., of the Neighbourhood of the Warwickshire Coal-field

These rocks may be classed into five or six more or less distinct groups. I. Syenitic Rocks (Croft Series). II. Andesite and Andesitic Tuffs (Caldecote Series). III. Hartshill Quartzite with Breccia at its base. IV. Diorites. V. Andesites or Diorites containing Augite. VI. Basalts or Diorites containing Olivine. The three last groups appear to graduate into one another, and seem to correspond with similar rocks described by Mr. Allport. Many of the specimens examined are in a more or less advanced stage of decomposition, calcite, serpentine, pyrites, etc., being very commonly present.