Two maps show the likely extent of glaciers on and around Haida Gwaii about 30,000 to 31,000 years ago when ice sheets began advancing west from the mainland, and about 17,000 to 19,000 at the peak of the last ice age. The possible location of a “Hecate Refugium” is shown by the question mark, while MP and CB mark fossil-sampling sites at Mary Point and Cape Ball. (Rolf Mathewes, John Clague/Quarternary Research 2017)

Two maps show the likely extent of glaciers on and around Haida Gwaii about 30,000 to 31,000 years ago when ice sheets began advancing west from the mainland, and about 17,000 to 19,000 at the peak of the last ice age. The possible location of a “Hecate Refugium” is shown by the question mark, while MP and CB mark fossil-sampling sites at Mary Point and Cape Ball. (Rolf Mathewes, John Clague/Quarternary Research 2017)

Study re-traces the geology and environment of ice-age Haida Gwaii

Study maps likely location of an ice-free “Hecate Refugium” east of present-day Moresby Island.

Biologist Rolf Mathewes got a heavy-duty surprise when he tested some fossils collected years ago from the sea cliffs at Cape Ball and Mary Point.

Among the tiny bits of pollen, spores, twigs, beetles, mosses and tadpole shrimp, Mathewes found something totally unexpected: dinocysts.

Dinocysts have nothing to do with dinosaurs. They act something like seeds for a microscopic marine creature called a dinoflagellate.

Still, it was a big surprise because while Cape Ball and Mary Point are right by the sea today, Mathewes dated the dinocysts to a time just before the peak of the last ice age, about 20,000 years ago — a time when global sea levels were about 150 metres lower and most of Hecate Strait was dry land.

To Mathewes and his geologist colleague John Clague, the little dinocysts are a sign that when tongues of the giant Cordilleran ice sheet finally crept their way west from the Skeena and Nass River valleys and across to Haida Gwaii, the weight of all that ice actually pushed the islands down close to the lowered sea.

“On Haida Gwaii, we have some of the best evidence for the fastest sea-level change recorded anywhere on the coast,” said Mathewes, who has been re-tracing the islands’ paleo-environment for the last 30 years.

“If there were people living on the coast, building along the beach, they would find over a short period of years that the sea would come up into their villages.”

Mathewes and Clague recently published a study collecting several new findings about Haida Gwaii’s ice-age geology and environment.

It includes the first map showing the likely location of what they call the “Hecate Refugium” — a large area of land east of present-day Moresby Island that was probably ice-free even at the peak of the ice age.

With so many unique species and sub-species on Haida Gwaii, biologists in the 1960s were among the first to suggest the islands were re-populated by plants and animals that waited out the ice age in such a refuge.

One such species is Calder’s lovage — a short, parsely-like plant with white flowers that not only survived here during the last ice age, but also the one before, some 60,000 years ago.

Geologists were slower to find evidence that fit the picture.

“Most geologists had favoured the idea of tabula rasa, the clean table — that ice came across from the mainland, right to the continental shelf edge, and just wiped out everything on Haida Gwaii,” Mathewes said.

John Clague was the first person to really buck the theory.

“His research on the glacial geology and his work with me made it very clear that Haida Gwaii had its own little ice cap that started in the mountains and probably left some areas ice-free,” he said.

While at one time ice did cover all but a few mountaintops on present-day Haida Gwaii, most of it was thinner and quicker to melt away than the huge ice sheet that blanketed nearly all of B.C.

At its maximum, the mainland ice only ever covered part of northeast Graham Island — people can still see the grooves where it met Haida Gwaii’s own ice cap and got pushed north and west along Dixon Entrance.

In the “Hecate Refugium” area east of Moresby, geologists can find no such grooves, scouring, till, or moraines to suggest it was ever overrun by glaciers. Similar evidence suggests there were more ice-free areas along the Alaskan panhandle, Prince of Wales Island and the Aleutians.

But the Holy Grail of all of this research is still missing, said Mathewes. No one has been able to find a sample of organic material that actually built up in one of those refuges during the peak of the ice age, most likely in an ancient lake or pond.

“It’s now under 100 metres of water,” he said.

“The best we have are some cores from nearby northern Hecate Strait, which date back about 16,000 years, just after the glaciation ended.”

Even in ice-free areas, little life would have survived the cold, miserable peak of the ice age, when even the Hecate Refugium probably looked like Arctic tundra.

“Finding organic deposits from plants and animals that might have been there at the time would be a real longshot — it’s possible, but no one has done it,” said Mathewes, who will soon join Clague in retirement but plans to visit Cape Ball this fall to see if storms have exposed any new surprises in the layered sea cliffs.

“You never know what you’ll find until you look.”