The Seismic Reflection method uses seismic energy (created by hammer impacts, accelerated weight drops, explosives, or vibroseis trucks) which gets reflected from geologic boundaries that have a velocity contrast. Seismic Reflection is used extensively for large-scale exploration projects, especially within the petroleum and mining industry.  Reflection is not used quite as often in near-surface applications. However, in certain shallow investigations it can be very useful for mapping lithology boundaries and more complex geologic structure, such as faults, for geotechnical engineering, environmental contamination flow modeling, or groundwater exploration/resource projects.  Additionally, it has proved successful for imaging and/or detecting earth fissures, paleochannels and steeply-dipping rock formations.