From the Field: Last day before departure

July 26

It’s our last full day here. Tomorrow morning we fly back south to Winnipeg - if the weather cooperates. The forecast is calling for possible thunderstorms all the way up the west coast of Hudson Bay past Arviat to Rankin Inlet and Baker Lake, where our flight originates. Typical … I don’t think I’ve ever managed to get out of Churchill on schedule! Much to do over the next 24 hours, including final packing of fossils and equipment, hauling everything to the shipping terminal for rail transport south, dealing with the vehicle rental, finalizing invoices for our stay at the Studies Centre, and touching base with one or two key contacts in town. The planning and logistical groundwork for all fieldwork in the natural sciences is made up of many such mundane tasks - it starts months (or even years) in advance, carries on through the entire time you’re in the field, and doesn’t ever seem to end. But it’s ALL worth it for the chance to make that one tiny discovery that pushes the science forward another incremental step.

Down to the last details - affixing labels to all the crates, boxes, tubs, and pails (left to right - Graham, Sean, Debbie, and Matt). The old Churchill Northern Studies Centre buildings - including our lab facility - were once part of the rocket range complex (constructed in part by the US military), and vestiges of that past still linger in places (below).

With most of the errands run, and all the gear (including our requisite bear deterrents) sitting on a pallet in a warehouse awaiting shipment, there’s little we can still do in terms of fieldwork. But it’s difficult to stop, and we make one last foray to a spot on the coast where the sight lines are good and we can stay within a few metres of the truck. A careful scan reveals no white furry threat in the vicinity, so we pile out and scramble around on our hands and knees picking through an innocuous-looking patch of bare gravel. No ordinary gravel, this … it is a part of a beach ridge deposit marking a former “high stand” of Hudson Bay, and mixed in amongst the pebbles are countless shells and shell fragments. These are “proto-fossils” - probably a thousand years old at most – representing some of the invertebrate animals that lived on the sea bed when the salty waters of the bay lapped higher on the shore. In some places around Hudson Bay, a succession of almost 200 ex-beach ridges such as this one step inland for many kilometres. This whole staircase-like package records the complex interplay between fluctuating sea levels and the inexorable rise of the land surface (known as isostatic rebound) after the last great glacial ice sheets melted from the region 8,000 years ago. But that’s another story, and we simply wish to sample the shelly remains captured on this single not-so-ancient shore. Not surprisingly, given their relatively young age, all of the forms we find are still represented in the shallow marine fauna of modern Hudson Bay.

Signs of the history of the Churchill Northern Studies Centre buildings.

The truck is loaded and ready to roll to the shipping terminal. Unfortunately, the train trip south will be delayed for a few days due to an earlier derailment on the single line connecting Churchill with the rest of the world … an annual occurrence it seems!

Over the course of a week, our dust-covered 4x4 became the site of a see-saw battle for graffito supremacy, as palaeontologists and ornithologists vied for prime message impact. The palaeontologists claimed victory in the end, just before departure-morning rains flushed all efforts away! For an amusing analysis of this friendly dirt-based rivalry, check out Graham Young’s clever post at: http://ancientshore.com/2011/07/29/evolution-and-extinction-of-the-f-150...

A sampling of the old beach ridge biota includes shells of familiar molluscs such as scallops and small clams, and disarticulated plates from small acorn barnacles (a crustacean arthropod specialized for sessile life). There's a real treat for palaeontologists, too - numerous fragile brachiopod shells, like the one atop the scale card. Abundant and diverse as fossils in Palaeozoic marine rocks, brachiopods are relatively few and far between in modern oceans. The single species we find in these old gravel deposits still inhabits Hudson Bay today. (Brachiopods are superficially clam-like in that their mineralized shells consist of two separate "valves" hinged together around a soft body, but there the resemblance ends. Major differences in shell symmetry, soft anatomy, development, and ecology indicate brachiopods and molluscs are only very distantly related.)

Fortunately, our collections of beach ridge shells are small and light enough to go in personal luggage, so it’s back to the Studies Centre to pack up and make all those final preparations for departure tomorrow.