 In the last several decades, with the location, investigation, and reporting of a growing number of sites with reliable dating, more and more American archaeologists now believe the western hemisphere was occupied at least several thousand years prior to the appearance of diagnostic Clovis materials.Most of these sites are widely spaced geographically and do not contain an extensive array of associated lithic materials that would show a diagnostic pattern of tool production and use.An attempt to define the characteristics of these older technologies can best be accomplished by investigating sites which are both well-stratified, containing both the older and Clovis materials—in order to compare technologies in use in the same location under similar conditions—and show evidence of extended periods of occupation where a wide range of activities took place employing the whole array of lithic tools.