Fish Cove

Fish Cove Rhyolite
Lake Superior Shoreviewer
Keweenaw County # 118

Park your car at Smith Fisheries and walk east along the shore, past the mouth of the Montreal River to Fish Cove, a small intrusive rhyolite body which crops out along the shore.  Across the pebble beach west of the main rhyolite body is a rhyolite dike outcrop.  The Keweenaw Fault is within a few meters of the shore here at Fish Cove, so the rhyolite is near the lowest part of the Portage Lake Volcanics.

Fish Cove was the subject of detailed field and lab studies by Bornhorst (1975). The intrusive is geochemically zoned with its interior richer in K, Rb and Ba, possibly because of crystallization along its borders.  The map at left shows where other rhyolites are located.