The summit of Hart Side is mainly grassy but with a scattering of rocky boulders showing through the grass. Some small cairns have been built on it, and there is another cairn some north of the summit, but the most unusual features are a long east-west trench which has been dug a few yards to the south, and a shallow hollow measuring just to the north. The trench was probably dug by prospectors looking for an extension to the vein being mined beneath Green Side, and the hollow may have been the site of some shelter. A vigorous programme of exploration, both underground and on the surface, was begun in 1947 when it was clear that the Greenside Mine could not last much longer, but nothing was found. In Alfred Wainwright's 1955 drawing the trench looks much cleaner and fresher than it is today