Stop # 2 is reached by walking down the dirt road (on your right) to the sand and gravel beach. This point bar is an excellent spot for lunch (or a swim!). We will walk about 100 yards upstream to exposures of gabbroic and ultramafic cumulates.

Although these initially look like sedimentary rocks, we are looking at igneous layering. The layers strike to the northeast and dip toward the northwest. The igneous layering is discontinuous in some places. The layers consist of darker, pyroxene and olivine rich layers and lighter, plagioclase and pyroxene layers.

The gabbro is interpreted as originally forming at a divergent plate boundary. Partial melting of the underlying mantle produces the gabbro-rich magma chamber above the peridotite. Layering of the gabbro may be due to either crystal settling (by density?) within the magma chamber or a segregation process related to the chemical stability of minerals. Good examples of layered gabbro exist at stop #2. Above the gabbro is a transitional area of gabbro and intruding mafic (iron and magnesium-rich) dikes. Above these exposures are exposures composed almost entirely of sheeted dikes with only a small portion of gabbro.