This province consists of four north-south-trending belts of metamorphic and igensou rocks that formed in an oceanic setting and subsequently collided with the North American continent about 150 million years ago. Completely folded and faulted rocks are bounded by belts of sparsely vegetated bands of serpentine.
Oregon Caves National Monument lies within an enormous fault-bounded block of marble. The historic gold-rush town of Jacksonville remains today as evidence of the area's colorful gold-mining history.
