emailIsland View Beach Regional Park
Learning Centre
Natural History
The story is in the sand
A lot happens to sand at Island View Beach. Halfway between Cordova Spit and the sand cliffs of Cowichan Head, sand from Island View Beach flows like a sluggish river out to the spit and sandbars offshore. The rich intertidal life of the sands and cobbles faces the barrage of the sea, while the dunes and saltmarsh provide a shifting refuge for a rare community of plants and animals clinging between the two worlds of ocean and earth. It's a dynamic ecosystem — one of few like it in the Capital Region.
First there was heat
Volancoes erupted frequently during the early years on what is now Vancouver
Island.
The island was part of a large, drifting piece of crust geologists call
Wrangellia. About 100 million years ago, it collided with the ancient
edge of North America. In the collision the island was crushed and deformed,
its surface uplifted and eroded. The rocks of Mt. Newton and Bear Hill
are remnants of the granite that formed the deep roots of some of those
volcanoes. Towering Mount Baker to the east is evidence of more recent
volcanism arising from the melting of the Pacific Ocean floor as it
descended beneath the edge of the continent.
Then there was ice
For over two million years, much of the northern hemisphere was periodically covered with moving sheets of ice. During the latter stages of the last ice age, beginning about 30,000 years ago, a valley glacier called the Cowichan Ice Tongue reached as far south as nearby Mount Newton. As the ice melted, thick beds of gravel and sand were laid down. In these local gravels, bones of ice-age mammals such as mastodons have been occasionally found poking through the beach surface.
About 15,000 years ago, an ice sheet about one kilometre thick covered the surrounding hills. As the ice advanced, gravel and sand deposited from waters melting along its front were over-ridden by the ice and moulded into streamlined hills, called drumlins, oriented in the direction of the southward ice flow. James and Sidney islands, the two closest to the beach, and the ridge to the west behind Island View Beach are such drumlins.
Finally water
About 12,000 years ago, melting icewater flooded the now-depressed land and submerged the peninsula. Salish First Nations people refer to this period in their oral history as "the time of chaos." Flood stories document the re-emergence of the land, giving rise to the name of Saanich, which means "land rising up." The land literally rose up after the weight of the ice was removed. Mount Newton ("the first place of refuge") and Bear Hill poked out as islands in the inland sea. The drumlins surfaced, geologically speaking, like whales. Lagoons drained and formed saltmarshes. Waves cut away at the base of the drumlins and formed the steep cliffs that you see at Cowichan Head to the south and James Island directly offshore. Finally, currents and tides started carrying the sand north down the beach to the spits and sand bars.
The Saanich People moved with the shorelines. They took advantage of the natural harbours that formed behind spits, living off the bounty of wildlife living on the sand and saltmarsh. They harvested clams, crabs, seabirds and plants of the saltmarsh and dunes for food and basketry.
Sea levels stabilised around 5,000 years ago. Great forests of western red cedar and sword fern grew up in the swamps. Douglas-fir climbed to 100 metres in height on the better drained soils of the drumlins. The dunes gradually reclaimed the sea with colonising plant species such as sand verbena and native evening-primrose. Both plants blew in or washed up from the unglaciated south.
Sandy Shores
Life on a sandy shore pounded by waves has no chance of hanging on unless it goes underground or can fly away. In every handful of sand, you'll find hundreds of organisms, from microscopic worms and diatoms to clams and shrimp, depending on where in the intertidal zone you look. Food for these creatures is gleaned from between the cracks of sand or combed out of the water by filter feeders. The narrow, specialised beaks of shore birds probe the sand for these invertebrates. The tide line in spring and autumn is the best place to watch for these small birds. Keep your distance so you don't tire them out. Ensure dogs are on the trail and under control so they don't chase these flocks of tiny birds.
Dune Systems
To people who study oceans, beaches appear to be living things. They constantly change. They advance and retreat. They are starved or nourished according to the currents, storms and prevailing winds. How much beaches build up depends on the supply of sand and logs they can store behind them and in front of them. When the sea attacks, the wind carries sand from the berms and dunes to the foreshore to build up sand bars.
Dune Plants
A mound of sand held together in a jumble of logs and plant roots sits on the high tide line. This is called the berm. From the berm back across the dunes to the forest lies a succession of different plant communities. Each species has developed its own strategy for survival. The first plants you encounter on the berm are American searocket, orache and gumweed — hardy pioneers that withstand drought and wind blasts with their succulent or sticky leaves. Dune wildrye and bluegrasses anchor each other with underground stems called rhizomes. In the foredunes, silver sandbur and beach knotweed start appearing. Silvery hairs and curling leaves enable these plants to hold moisture. Bonsaii Pacific crabapple trees cling as stunted shrubs just before the dune slack, which is marked by large-headed sedge strung across the sand in lines. In the backdunes, the greatest number of rare species occur, such as yellow sand verbena with its scented flowers and fleshy oval leaves. Please stay on the trail so you don't disturb these vulnerable plants.
Drilling for history - evidence of the rise and fall of sea levels
Scientists sampled the soil at two locations close to Island View Beach Regional Park. A 14-metre earth core was drilled on the sand spit north of the park access road. The medium to coarse sands in the core record a long period of beach-like environments at a time when the sea level was lower than at present. The sediments of the spit were swept here by waves and longshore currents from the sandy bluffs of Cowichan Head to the south.
West of the spit, scientists dug pits that revealed buried peat moss lying beneath a shallow layer of brackish-water mud. The peat, dated at roughly 2500 years of age, suggests a sudden down-warping of the land following a large earthquake. Evidence of similar events of about this age has been found at several locations on southern Vancouver Island and the Lower Mainland.
Within the intertidal zone at the north end of the Cowichan Head bluffs, researchers discovered fossil tree stumps carbon-14 dated at approximately 2040 years of age. These stumps provide further evidence of a rapid rise in sea level during the past 5000 years.
