The view of Boston from East Point, Nahant. In the foreground Cambrian age limestones are seen to dip to the east. Late Pleistocene glacial till overlying bedrock at East Point, Nahant. Great Ledge Block - a Ordovician age dolerite sill intruded into the Cambrian Weymouth Fm. Another view of Great Ledge Block A basalt dike has been eroded by waves to form a narrow ravine.
Waves attack fractures and other weak spots to wear away the coast.
Students descend the rocks to examine a fault. Students climbing back up after examining a fault. Before Lunch students examine the many rock types found in the beach gravel of Dive Beach. Rock types include local rocks such as limestone, mudstone, basalt, gabbro, and dolerite. Non-local pebbles include glacial erratics such as granite, rhyolite, gneiss, and schist.