The regional geology comprises volcanic rocks of the Lower Jurassic Hazelton Group overlain by Tertiary volcanic rocks of the Endako Group and Miocene plateau basalt. These supracrustal assemblages have been intruded by intermediate to felsic plutons of the Coast Plutonic Belt on the western side of the Intermontane Belt. The degree of deformation of Jurassic rocks increases towards the western side of the Intermontane Belt. Most of the Hazelton Group has been subjected to nonpenetrative deformation but towards the west deformation becomes more intense and penetrative.

The Tweedsmuir Park showing consists of silver and zinc mineralization within Hazelton Group tuff and volcanic breccia adjacent to a small granodioritic stock. Other than the record of its locality on Geological Survey of Canada Map 1202A, nothing more is known about this occurrence.