TIME About 45 minutes. Mechanical weathering is the process of breaking down bedrock into smaller fragments by physical as opposed to chemical means. Rock weathering, although it seems to occur ever so slowly in human terms, is an extremely significant part of the rock cycle. Weathered rock materials are called sediments and are the structural basis for ALL the worlds soils. Sediments can also be compacted into sedimentary rock.
Rock weathering rates vary widely depending on mineral content, texture, rock type, and climate.
Differential weathering, varying weathering rates for two or more rock types in physical contact with each other, has given rise to some of the world's most breathtaking scenery such as the coastlines of Maine, New Brunswick, and Nova Scotia. The rock formations at Two Lights State Park, Cape Elizabeth, Maine are an excellent example. The rock types should be of more or less uniform size in the 1 x 2 inch range. After discussion of the results of this activity, the following exercise will provide immediate reinforcement and local application of what the students have just learned. Collect a sample from the feature, or have the class visit it if feasible, and see if the class predictions were correct.