In the sequence of North Americanprehistoric cultural stages first proposed by Gordon Willey and Philip Phillips in 1958, the Lithic stage was the earliest period of human occupation in the Americas, occurring during the Late Pleistocene period, to time before 8,000 B.C. (before 10,000 years ago). The term "lithic stage" refers to the cultures of the post-glacial hunters and and collectors in South America. The stage derived its name from the first appearance of Lithic flakedstone tools. This stage was conceived of as embracing two major categories of stone technology: (1) unspecialized and largely unformulated core and flake industries, with percussion the dominant and perhaps only technique employed, and (2) industries exhibiting more advanced "blade" techniques of stoneworking, with specialized fluted or unfluted lanceolate points the most characteristic artifact types. Throughout South America, there are stone tool traditions of the lithic stage, such as the "fluted fishtail" that reflect localized adaptations to the diverse habitats of the continent. 
During the lithic stage people lived in rather small, mobile groups that survived on hunting, fishing, and plant gathering. The intensive and continual use of wild plants and animals eventually led to genetic changes to some of the species and ultimately to domestication by human groups. This lifestyle continued until around 5000 BC when people started use domesticated plants and animals. 
One of the leading figures is Alex Krieger who has documented hundreds of sites that have yeilded crude, percussion-flaked tools. The most convincing evidence for a lithic stage is based upon data recovered from sites in South America where such crude tools have been found and dated to more than 20,000 years ago. 
The time encompasses the Paleo-Indian period that subsequently is divided into more specific time terms such as Early Lithic stage or Early Paleo-Indians and Middle Paleo-Indians or Middle Lithic stage. Examples include the Clovis culture and Folsom tradition groups.