There are three main inliers of Silurian rocks in the Pentland Hills:—

(1) Lyne Water—North Esk Reservoir Inlier, which includes the Gutterford Burn section with the well-known Eurypterid and Starfish beds and the Deerhope and North Esk sections in which there is a passage upwards into red beds often referred to as “Downtonian”.

(2) Bavelaw Castle Inlier, with beds of an age similar to those in the Gutterford Burn.

(3) Loganlee Reservoir Inlier, yielding a few graptolites in strata partly corresponding with those of the Bavelaw Castle Inlier, and with an important assemblage of Silurian corals in the overlying Lower Old Red Sandstone conglomerate.