This is the San Andreas Fault, remember Faults are everywhere, not just at transform boundaries. This particular fault is hundreds of miles from a transform boundary.
Forms of Mechanical Weathering breakdown rock without changing it's composition. This means that all the ingredients in the rocks stay the same. They include Abrasion, Ice Wedging, Plant and Animal Action.
Forms of Chemical Weathering breakdown rock while changing the composition. This means that some chemical change has occurred and the ingredients of the rock have been removed or altered. Acids from plants or pollution, dissolving water, and oxidation all take part in this type of weathering. Certain types of animals even eat minerals directly out of rocks causing chemical weathering. Deer are a classic example of this when they lick rocks to get salt minerals.