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Nanaimo River Estuary

A cache by Mudgekin Send Message to Owner Message this owner
Hidden : 10/08/2014
1.5 out of 5
1.5 out of 5

Size: Size: other (other)

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Geocache Description:


After getting to the parking lot for the Chase River Estuary Park follow the Estuary trail to your left. This no longer a loop trail as indicated on the sign. This trail will take you to a viewing platform with informational signs. Some of the signs have been vandalized so hopefully the city will repair them soon. Take the time to visit the Ridge Trail as well so see an overall view of the estuary.

Just south of downtown Nanaimo there is a wonderful park known as Chase River Estuary park with 1.2 km of trails. The shorter walk (Estuary Trail) includes a boardwalk nearly at water level, amidst the tall grasses of a little valley. The longer loop (Ridge Trail) follows a path on the other side, parallel to an old rail line. This trail provides two kinds of views; there is the Chase River and its boardwalk on one side, and the Nanaimo River estuary and ocean on the other side of the tracks.

What is an estuary?
An estuary is a partly enclosed body of brackish water (more salinity than fresh water) along the coastline with one or more rivers or streams flowing into it. They form a transition zone between fresh water rivers and saline marine conditions. They are subject to several influences such as waves, tides, fresh water and sediment. These variables provide high levels of nutrients making estuaries highly productive habitats. The Nanaimo River estuary is the largest estuary on Vancouver Island. As the rivers flow into the ocean sediment is deposited along the banks and basin. A delta is formed when the river deposits its material faster than the sea can remove it.

There are five major types of estuaries - classified by their geology or how they were formed. The five major types of estuaries are coastal plain, bar-built, delta system, tectonic, and fjord. 
Coastal Plain – Formed at the end of the last ice age - as the ice melted sea levels rose and covered low lying river valleys
Bar-built – Occur when when sandbars or barrier islands are built up by ocean waves and currents along coastal areas fed by one or more rivers or streams
Delta system – Deltas form from sediment carried by a river as the flow leaves its mouth.
Tectonic – formed by the crustal movements along fault lines causing water to fill in. This type is small in number
Fjords – found along glaciated coasts and characterized by a deep basin that filled with water when the glaciers melted

Freshwater estuaries do not contain saltwater, they are unique combinations of river and lake water, which are chemically distinct. Unlike brackish estuaries where mixing processes are typically tidally driven, freshwater estuaries are most often storm-driven. In freshwater estuaries the composition of the water is often regulated by storm surges and subsequent movement of lakewater.

While estuaries and coastal wetlands make up less than 3% of BC's coastline they provide habitat to over 80% of all fish and wildlife species. Half of BC's 8 most important estuaries are on Vancouver Island. Nanaimo River estuary is a highly productive habitat providing for migratory birds, plants and fish. Despite their importance, over 40% of estuaries throughout BC are threatened by development, modification, and pollution. 

The banks of many estuaries are among the most heavily populated areas of the world, with about 60% of the world's population living along them causing degradation and overuse. The Nanaimo Estuary has a particular past and has garnered much attention. The black sediment found along the shoreline was in question and caused concern. At first it was thought the sediment came from log storage which is still in practice but when no wood fibres were found the cause was attributed to the coal processing plant on the shore. Coal mining in Nanaimo was prevalent for 108 years and during that time about 50 million tonnes was mined, mostly in the Nanaimo River and estuary. While good records were not kept it is assumed the coal mining practices contributed to the black sediment.  Studies are ongoing to determine the ongoing degradation.

To log this earthcache send the answers to the owner by email. Please to not include them in your log. 

1) What is the classification of the Nanaimo River Estuary? Why do you think this?

2) What two rivers have worked together to form this estuary?

3) What upper land influences have contributed to the sediment?

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