Complex sentence: The rush is credited with instigating European-Canadian settlement on the Mainland of British Columbia, as well as catalyzing the founding of the Colony of British Columbia and the beginnings of a road infruastructure and the founding of many towns.
Split into simpler sentences: The rush is credited with instigating European-Canadian settlement on the mainland of British Columbia. It was the catalyst for the founding of the Colony of British Columbia, the building of early road infrastructure, and the founding of many towns.