Several quarries in the neighbourhood of Shildon, near Bishop Auckland in South Durham, display interesting sections of the Lower Magnesian Limestones and the beds on which they rest. At present the most instructive is that at East Thickley, near Shildon railway station, and as there seems a probability in the near future of this quarry becoming obscured by pit refuse, a record of the section exposed in it seems to be desirable. A large part of the rock-face has already been so obscured. A short distance south-east of this one other quarries exist closely adjoining the railway, but they are now almost entirely filled up with rubbish though sections in the railway cutting may still be seen. About a mile south-west of Thickley across the railway a quarry is at present being worked near Midderidge Grange, and seems to be the one in which important reptilian and other vertebrate remains were found in the Marl Slate many years ago. Notable among these is the headless skeleton of Proterosaurus Huxleyi Hancock & Howse, each bone of which has the interior filled with galena. This and other important specimens are now in the Hancock Museum at Newcastle-on-Tyne. At present, however, the only rock visible in Midderidge Quarry is the dolomitic Lower Magnesian Limestone, in which no fossils are to be seen. These quarries are either, as in the case of East Thickley, situated on the junction of the Permian with the Coal Measures, or, in the case of Midderidge, very close to the junction.