Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:This leads to the formation of a knickzone, where a slowly eroding plateau with smooth hillslopes is juxtaposed to a rapidly eroding reach with elevated channel steepness, high erosion rates, and steep hillslopes (Safran et al. 2005; Blodgett and Isacks 2007).
Category: