Make a Comment • Email Link • Send Letter to Editor IPFS News Link • Geology Constructive Collisions 04-20-2013 • arclein he mountain ranges of the North American Cordillera are made up of dozens of distinct crustal blocks. A new study clarifies their mode of origin and identifies a previously unknown oceanic plate that contributed to their assembly. Watch Streaming Broadcast Live: LRN.fm Watch live shows and archives TV Live Chat Telegram Share this page with your friends on your favorite social network: