In April 2015, approximately 22 miles of continuous seismic profiling (CSP) surveys were collected on the Cedar River in Iowa. The swept frequency (chirp) CSP subbottom profiler was used to characterize the unconsolidated materials above the bedrock. The CSP subbottom profiler is an acoustic sound source that travels through the water column and reflects off the bottom and sub-bottom layers and is received at the transducer. (see Collecting resistivity and seismic data Cedar River IA 2.JPG. Applying a water column velocity, the two-way travel time can be converted to distance. CSP methods provide the depth to water bottom, and when sufficient signal penetration is achieved, CSP can be used to delineate the depth of subbottom layers and topography of the bedrock surface.