which technique is used here?
heating
Lithic reduction
In some cases the heating changes the colour of the stone.
what is referred as bull run river? It is a tributary of the Sandy River. where is it situated? U.S. state of Oregon who were its first inhabitants? Paleo-Indians how is the climate here? mild climate is it related to any energy producing project? UNANSWERABLE how is the above mentioned group of people classified? They  are generally classified by lithic reduction or lithic core "styles" and by regional adaptations. when did they migrate to america? 17,000 years ago you mentioned a kind of reduction in you answer, what is that? It is the process of fashioning stones or rocks from their natural state into tools or weapons by removing some parts. what is its index? One of the measurements is the geometric index of reduction.
wiki:1155885
Lithic reduction [SEP] Techniques
Alongside the various percussion and manipulation techniques described below, there is evidence that heat was at least sometimes used. Experimental archaeology has demonstrated that heated stones are sometimes much easier to flake, with larger flakes being produced in flint, for example. In some cases the heating changes the colour of the stone.