What type of unconformity forms when sedimentary rocks overlie either igneous or metamorphic rocks?

Gold is not now being extracted from seawater. why not? a. it would be too disruptive to marine life to develop any marine mineral resources b. there is no gold in seawater c. we don't know how to extract minerals from seawater d. it would be too costly and difficult to separate the small amount of gold from the very large amounts of halite and other minerals

Where is the vascular system located

Amajor rite of passage for the maori men of was to receive ta moko, or facial tattoos. a. australia b. new zealand c. papua new guinea d. southeast asia