Saturday, 30 January 2010

STEPPING-STONE ISLANDS


Steeped in mist and mythology, the islands of the Queen Charlottes abound in local lore that surrounds their beginnings. Today the Hecate Strait is a tempestuous 40-mile wide channel that separates the mist-shrouded archipelago of Haida Gwaii from the BC mainland.

Haida oral tradition tells of a time when the strait was mostly dry, dotted here and there with lakes. During the last ice age, glaciers locked up so much water that the sea level was hundreds of feet lower than it is today. Soil samples from the sea floor of Hecate Strait contain wood, pollen, and other terrestrial plant materials that tell of a tundra-like environment.

Whether or not the strait was ever completely dry during these times, it seems that it did at least contain a series of stepping-stone islands and bridges that remained free of ice.

An ancient Haida tale, recorded in the late 1800s by a Hudson’s Bay Company trader, records the island's glacial history. Scannah-gan-nuncus, a boy who lived in the village now called Skidegate, had canoed up the Hunnah, a tributary to Skidegate Channel. Today, the Hunnah is a rocky creek, seldom deep enough to navigate.

The Haida the legend accurately records that it used to be several times deeper. Tired from paddling upstream, Scannah-gan-nuncus landed to take a nap. “In those days at the place where he went ashore were large boulders in the bed of the stream, while on both sides of the river were many trees. While resting by the river, he heard a dreadful noise upstream. Looking to see what it was, he was surprised to behold all the stones in the river coming toward him. … all the trees were cracking and groaning … he went to see what was crushing the stones and breaking the trees. On reaching them, he found that a large body of ice was coming down, pushing everything before it.”

Scannah-gan-nuncus’ experience with the glacier would have been familiar to the inhabitants of the Queen Charlottes. Today, the highest peaks are often bare of vegetation and snow-covered during most of the year, but back in the time of the glaciers, these same local mountains were the birthplace of advancing ice.

Precipitation and a significant drop in temperature gave rise to the Queen Charlottes ice-sheet, a thick mass of flowing ice that ran tandem with the Cordilleran sheet in the Hecate Lowlands.

Strolling around today, you can see where the glaciers left their mark on the Islands’ U-shape valleys, once a steep V-shape, now scoured into a smooth by glaciers that also deposited the erratic boulders can been seen sitting like out of place sentinels on the beach.

Thursday, 28 January 2010

SALMON CHIEF: FOOD OF THE GODS

Salmon have permeated First Nations mythology and have been prized as an important food source for thousands of years.

For the Salish people of the Interior, salmon was the most important of the local fishing stock and salmon fishing season was a significant social event which warranted the nomination of a “Salmon Chief” who directed the construction of the hooks, weirs and traps and the distribution of the catch.

In the Interior of the province, archaeological evidence dates the use of salmon as a food source back 3,500 years. Sheri Burton and Catherine Carlson were able to isolate and amplify mitochondrial DNA from salmon remains from archaeological sites near Kamloops, and identified the species as Oncorhynchus nerka, or Sockeye salmon. No older salmon remains had been found in the Kamloops area until the 1970’s, when fossil salmon concretions were collected on the south shore of Kamloops Lake.

These concretions were originally dated as Miocene (24 – 5.5 million years old) by the Geological Survey of Canada, based on analysis of pollen grains found in the concretions. However, many local experts, including UBC geology professor W.R. Danner and the late geologists W.H. Mathews and Richard Hughes, suspected the remains were from the much more recent, Late Pleistocene epoch. But it was not until the early 1990s that Catherine Carlson and Ken Klein found definitive proof of this.

By good luck, the fish remains in the Kamloops Lake concretions had not been completely replaced by minerals – enough of the original organic bone collagen remained for radiocarbon dating. The corrected date is approximately 18,000 years. It is likely that erosion during the time of deposition had carried pollen down from Miocene layers in surrounding hills, to be deposited around the dead fish, causing the initial over-estimation of the age of the concretions.

An age of 18,000 plus years – sets the fossils firmly as the only salmonids of the Late Pleistocene in North America, a very significant find. The date also changed our ideas about the early climate of the Interior; the Thompson Valley could not have been covered by glacial ice for as long as originally thought.

It has long been accepted that the most recent series of ice ages began approximately 1.6 million years ago, beginning as ice accumulations at higher altitudes with the gradual cooling of the climate. Four times the ice advanced and receded, most recently melting away somewhere around 10,000 years ago. Ice retreated from southwestern British Columbia and the Puget Sound area around 15,000 years ago.

In the southern Interior, ice built up first in the northern Selkirk Mountains, then slowly flowed down into the valleys. Once the valleys were filled, the depth of the ice increased until it began to climb to the highlands and finally covered most of the Interior of British Columbia. Between ice advances, there were times when the Kamloops area was ice free and the climate warm and hospitable.

Glacial ice was believed to have initiated its most recent retreat from the South Thompson area around 11,000 to 12,000 years ago, but salmon remains from 18,000 years ago suggest that it may have actually began its northwest decline much earlier and indicating a much warmer climate in the Interior than archaeologists or geologists had originally estimated.

Eighteen thousand year-old salmon also challenge the archaeological notion that aboriginal people of the Interior have had access to salmon as a significant protein source for only a few thousand years. In the popular view, people living in the Okanagan and Thompson Valleys were felt to have moved to settlements that were semi-permanent about 4500 years ago.

By that time they would have had a seasonally regulated diet composed primarily of salmon and supplemented by local game - deer, elk, small mammals – and available shellfish, birds and plant foods. If salmon were present much earlier, it is possible that this pattern of food utilization may have arisen earlier than thought.

Richard Hughes had originally identified the fossilized Kamloops salmon as Oncorhynchus nerka or Sockeye salmon, the same species found in the 3,500 year old archaeological sites. But, using the carbon-13 isotope ratio, Klein and Carlson were able to determine that these salmon did not feed on protein from a marine source and relied solely on a freshwater diet.

In other words, they could not have spent part of their life in the ocean, as modern Sockeye salmon do. Based on the specimens’ smaller heads and stunted bodies, the longest measuring in at a pint-sized 11.5 cm, Klein and Carlson feel that the fossils are likely Kokanee, a modern landlocked variety of Sockeye.

Here two people very precious to me celebrate life's many gifts from land and sea at the 1994 Hunt Memorial Potlatch.

HALE CREEK FOSSIL FIELD TRIP

Tuesday, 26 January 2010

Saturday, 23 January 2010

Wednesday, 20 January 2010

CHUCKANUT FOSSIL TRACKWAYS

Chuckanut Drive is much younger than other parts of Washington. The fossils found there lived and died some 40-55 million years ago, very close to where they are now, but in a much warmer, swampy setting. The exposures of the Chuckanut Formation were once part of a vast river delta. Imagine, if you will, the bayou country of the Lower Mississippi. The siltstones, sandstones, mudstones and conglomerates of the Chuckanut Formation were laid down about 40-54 million years ago during the Eocene epoch, a time of luxuriant plant growth in the subtropical flood plain that covered much of the Pacific Northwest.

This ancient wetland provided ideal conditions to preserve the many trees, shrubs & plants that thrived here. Plants are important in the fossil record because they are more abundant and can give us a lot of information about climate, temperature, the water cycle and humidity of the region. The Chuckanut flora is made up predominantly of plants whose modern relatives live in tropical areas such as Mexico and Central America. If you are interesting in viewing a tropical paradise in your own backyard, look no further than the Chuckanut. Images and tag lines: Glyptostrobus, the Chinese swamp cypress, is perhaps the most common plant found here. Also abundant are fossilized remains of the North American bald cypress, Taxodium; Metasequoia (dawn redwood), Lygodium (climbing fern), large Sabal (palm) and leaves from a variety of broad leaf angiosperm plants such as (witch hazel), Laurus (laurel), Ficus (fig) and Platanus (sycamore), and several other forms.

While less abundant, evidence of the animals that called this ancient swamp home are also found here. Rare bird, reptile, and mammal tracks have been immortalized in the outcrops of the Chuckanut Formation including tracks of Diatryma, a massive flightless bird that reached up to 9 feet in height and made a living in the grasslands and swamps of the Eocene.

Tracks of a type of archaic mammal of the Orders Pantodonta or Dinocerata (blunt foot herbivores), footprints from a small shorebird, and tracks from an early equid or webbed bird track give evidence to the vertebrates that inhabited the swamps, lakes and river ways of the Pacific Northwest 50 million years ago.

WANNERIA DUNNAE

Wanneria dunnaeis an impressive trilobite from British Columbia's Eager Formation, and one of the more striking specimens found at the original research site of the lovely Lisa Bohach, a paleontologist now working out of Alberta.

The site has changed over the years, both physically and politically, but the one constant is the exquisite detail of the specimens. Both Wanneria dunnae and Ollenelus ricei are commonly found here. I had a eureka moment there a few years ago when ambling up the path to the main pit. The sun hit a wily would-be hiking track on a bit of shale at just the right angle. Closer inspection showed it to be a Tuzoia, one of the rare arthropods to come from the area.

Tuesday, 19 January 2010

Tuesday, 12 January 2010

MOONLIT PADDLE

CROCODILIAN UPSTARTS: THE CRUROTARSANS

Dinosaurs, long hailed as the rulers of the Triassic almost lost the title belt to a group of crocodilian upstarts, the crurotarsans. In a short lived battle for survival, geologically speaking, the two groups ran head-to-head for about thirty million years with the Crurotarsi butting their massive skulls and narrow snouts against their evolutionary opponent and ultimate successors, the dinosaurs.

The Crurotarsi or "cross-ankles" as they are affectionately known, are a group of archosaurs - formerly known as Pseudosuchians when paleontologist Paul Serono, the darling of National Geographic, renamed them for their node-based clade in 1991.

LIMESTONE AND SALT AIR: GORDES

Tuesday, 5 January 2010

Saturday, 2 January 2010

Friday, 1 January 2010