Of Inoceramids and Isotopes

Abstract

To the north of Sucia Island lie the Canadian Gulf Islands, an isolated archipelago made up of the same Cretaceous strata we find on the U.S. side of the international boundary—the mixture of shale, sandstone, and conglomerate so typical of the Nanaimo Group formations. The Canadian Gulf Islands float like serene battleships off the coast, but getting to them is even harder than making port at Sucia. Unless you cheat (like the many smugglers in the region) and scoot across in a fast boat, the Gulf Islands are a long travel day from the United States. You have to take a British Columbia ferry out of the crowded Vancouver terminals, but once you are loaded aboard, conditions improve considerably; the sea voyage is spectacular as you head west, crossing the wide Strait of Georgia with the mountainous Vancouver Island looming in the distance. Once you arrive on these eagle-infested Canadian islands, it is clear that you are out of the United States: better beer, worse food, no Starbucks coffee (but mercifully no McDonalds either), and everywhere the lilt of Canadian English with the distinctive “ehs” creatively interspersed in every sentence. These islands are long and thin, carved by the glaciers with a north-south whim, and they form a rampart that seems to protect Vancouver Island from an encroaching North America. One of the longest of these islands is Gabriola Island. Its few, rare ammonite fossils tell us that its strata are not so old as the rocks of Sucia. Gabriola contains some of the youngest, and thus last-formed, rocks still of Mesozoic age in all of western Canada. Somewhere buried in its youngest rocks is a Cretaceous/ Tertiary boundary site, the boundary between the Mesozoic and Cenozoic Eras now thought to have been formed by the impact of a giant comet 65 million years ago.