Erosion: The removal and /or transportation of surface material by running water, moving ice or wind.

Mass Wasting: The downslope movement of surface material by gravity, but aided by water, ice, and wind. There are many types of mass wasting but the most common ones along Lake Michigan are slumps and flows. A slump implies the movement of a large block of earth material in one piece. Frequently it slips or moves along a curved surface. A flow suggests that the material moves like a slow flowing river or a spilled thick milkshake. Frequently these two types of mass wasting will blend at a location.

Longshore Transport: This refers to the movement of shoreline material like sand, clay and rocks parallel to the shoreline. Waves frequently hit the beach at an angle and part of the wave energy or force is parallel to the beach. This force moves material along the beach. The amount of longshore transport is strongly related to the wave size (height) and angle to the beach. To prevent longshore transport groins and jetties are constructed to collect the beach material. Groins look like docks or piers, but they let less water pass under them. There are many examples along Lake Michigan.

Lake Michigan Bluff Material Near Milwaukee: The Lake Michigan bluff material is composed almost entirely of glacial material deposited between 20,000-15,000 years before present. These are tills that are associated with the Lake Michigan Lobe of the Wisconsinan Glaciation. Lake Michigan was a preexisting river basin that was a natural lowland for the glaciers to occupy during glaciation. There are two different glacial tills exposed on the shore in Milwaukee County. The older till is gray in color and exposed at Grant Park. It is called the Oak Creek Till. The younger till called the Ozaukee Till is Bluedish in color and found in the north shore bluffs. Both tills have discontinuous layers of sand and silt interlayeBlue with the clay rich material. This inter-layering is one of the main reasons the slopes lose stability when they become saturated with water.