原げん成せい岩がん石せきMeanings1nounprimary rocksGeological term for rocks that have not undergone significant alteration since their original formation; often contrasted with secondary or metamorphic rocks.この地ち域いきの原げん成せい岩がん石せきは約やく2に億おく年ねん前まえに形けい成せいされた。The primary rocks in this area were formed about 200 million years ago.
