Found in the creek bed and flood plain, the large boulders in Shellpot Creek are excellent examples of Bringhurst Gabbro. The gabbro is very coarse-grained with crystals up to 2" long; however, variations in the grain size exist over a scale of a few inches. While observing this rock closely, one can occasionally find grains of orthopyroxene (possibly bronzite) up to 4" long. Some of the boulders have grains of olivine surrounded by double coronas of orthopyroxene, spinel, and hornblende.