In introduction, it should be stated that, where the sequence is fully developed, a number of marine limestones separated by non-marine strata occur in the uppermost part of the Calciferous Sandstone Series and lowest part of the overlying Carboniferous Limestone Series of Scotland, and that the junction of the two series is drawn by the Geological Survey at the base of the Hurlet Limestone. In Ayrshire the limestones below the Hurlet (or Dockra) Limestone are practically confined to a belt of country extending north and south across the northern part of the county. To west and east of this belt the Hurlet Limestone overlaps on to beds of volcanic detritus which overlie the Calciferous Sandstone volcanic rocks of the Clyde Plateau ( see Richey, 1925). Kilbirnie lies towards the west of the belt, and just west of this neighbourhood the westward overlap of the Hurlet Limestone has usually taken place. It is only in the Paduff Burn, north-west of Kilbirnie, that one of the Calciferous Sandstone limestones is still present. In the Kilbirnie district, and extending eastwards to Lugton, two facies of the Hurlet Limestone are encountered. One facies, which may be called the Trearne type (Richey, 1930, p. 146), consists of dominantly white or cream-coloured limestone (though usually containing small dark patches) often in massive beds. It is also characterised by abundance of well-preserved fossils, especially large encrinite stalks, many of them an inch in width, and medium-sized Productid shells. In the upper part of the limestone patches and layers This 250-word extract was created in the absence of an abstract