Weathering takes place when a rock is exposed to the "weather", in other words to
the forces and conditions that exist at the earth's surface. Both mechanical and chemical processes are important to weathering, and in most cases they act together to reduce solid rocks to fine-grained sediments and dissolved substances. Mechanical weathering provides fresh surfaces for attack by chemical processes, and chemical weathering weakens the rock so that it is more sustainable to mechanical weathering. The different types of weather are as follows :
Mechanical weathering : breaking down of rocks into smaller pieces ( also known as physical weathering )
The 4 different types of mechanical weathering are :
1. Frost wedging - when water expands when it freezes
2. Salt wedging - A layer of saltwater forms below a layer of freshwater due to differences in density. Crystals growing
3. Thermal Expansion & Contraction - Materials expanding or contracting due to changes in temperature
4. Exfoliation - taking a layer off ( release pressure )
Chemical Weathering : Change of chemistry of the rock and minerals into something else
The 3 different types of Chemical weathering are :
1. Dissolution - material that dissolves in water and goes to a solution with ions
2. Hydrolysis - Chemical reaction with water, reaction of silicate minerals with water to form clay
3. Oxidation -The process or result of oxidizing or being oxidized.
Important in the breakdown of many mafic minerals.
Many people get weathering and erosion confused but erosion is the physical removal of material by mobile agents such as water, ice and gravity.
the forces and conditions that exist at the earth's surface. Both mechanical and chemical processes are important to weathering, and in most cases they act together to reduce solid rocks to fine-grained sediments and dissolved substances. Mechanical weathering provides fresh surfaces for attack by chemical processes, and chemical weathering weakens the rock so that it is more sustainable to mechanical weathering. The different types of weather are as follows :
Mechanical weathering : breaking down of rocks into smaller pieces ( also known as physical weathering )
The 4 different types of mechanical weathering are :
1. Frost wedging - when water expands when it freezes
2. Salt wedging - A layer of saltwater forms below a layer of freshwater due to differences in density. Crystals growing
3. Thermal Expansion & Contraction - Materials expanding or contracting due to changes in temperature
4. Exfoliation - taking a layer off ( release pressure )
Chemical Weathering : Change of chemistry of the rock and minerals into something else
The 3 different types of Chemical weathering are :
1. Dissolution - material that dissolves in water and goes to a solution with ions
2. Hydrolysis - Chemical reaction with water, reaction of silicate minerals with water to form clay
3. Oxidation -The process or result of oxidizing or being oxidized.
Important in the breakdown of many mafic minerals.
Many people get weathering and erosion confused but erosion is the physical removal of material by mobile agents such as water, ice and gravity.
Mass Wasting
Shallow landslides, particularly debris flows, are a characteristic mass movement type that occur along the Sea to Sky Highway in British Columbia. Historically, there have been a number of debris flows along the Sea to Sky Highway that have caused property damage, blocked traffic, and resulted in the loss of lives. During the 2012 Winter Olympics that took place, the Sea to Sky highway was upgraded due to it being heavily at risk for Mass Wasting. The reason it was at risk was because in order for the highway to be built, they had to cut into the mountain side, creating an unstable slope that can only support the land above for a limited amount of time. Ways to reduce losses due to these events can include avoiding construction in areas prone to mass movement, build in a way that does not make naturally large slopes, and lastly, create water drainage. In general more water means more instability.
River Features in BC
An early stage river near the point of origin and in the mountains are termed young rivers. This stage you will typically see rapids, waterfalls, vertical erosion etc. The shape of the river valleys is a U-Shaped valley due to vertical erosion. caused by steep gradient resulting in erosion by abrasion and hydraulic. Once rivers leave the mountains their behavior changes and are termed mature river. The most common form of a mature rives is a meandering stream ( S-Shaped ). Erosion is now less vertical and more horizontal.
The final stage of a river is called the old stage. The land is flat and deposition is common resulting in meanders becoming much more developed, Oxbow lakes. Flooding becomes a common thing for old stage rivers. The flat land that this is termed a flood plain. When the slope of the land suddenly changes there is a sudden deposition from the river. If this material piles up above water level it is termed an alluvial fan. If this material piles up under water it is termed a Delta.
Based on the speed of flow and amount of water in a river, they carry sediments through four processes. Suspension, the carry of sediments through the flow of the water, completely afloat. Saltation, the carry of sediments through a bouncing motion, temporarily suspended in the water. Bed Load, rolled along the bottom of the river, but never suspended. Solution, the carry of sediments in a fluid form.
Ground Water
Did you know from all the water on this earth, 96% is salt water and the remaining 4% is trapped in glaciers, groundwater, and lakes + rivers. There are two factors that allow for a specific kind of rock mass to withhold water. The first being Porosity, percent of empty space in the rock or sediments. The second being Permeability, ability of a material to transmit fluids. Aquifers are rock that hold and transmit enough water to be used as a source, a good example of this is sandstone and limestone. There are 2 variations of aquifers. The first being an unconfined aquifer, being open to all kinds of intrusions from pollution or agriculture, which is not ideal for drinking water in most cases. The second being a confined aquifer, being pushed between two impermeable layers of rock, which is the ideal situation for a water well. This is due to the aquifer having a protective layer which blocks the flow of any liquids into it's supply.