The post-firing variability of fire-affected rock (FAR) recovered from a stone-cooking platform within a prehistoric stone grill was examined. This examination tested the physical properties of FAR recovered from site CA-SBR-3773, located the Crowder Canyon Archaeological District in San Bernardino County, California. There is a lack of archaeological research in this area of Southern California; however, this project established a fundamental perspective of thermal feature reuse and episodes of firing activity for prehistoric cooking features by examining the physical changes FAR experienced due to various heat exposures. Regional archaeologists often encounter these features as they speckle the landscape of upland desert regions in California. This research is an experimental project that compares the cultural stones’ properties to those of non-cultural origin, which have been fired various times during controlled replicative experimentation. The end comparison identifies the FARs’ change in physical conditions. Repeated exposure to high temperatures has a direct relationship to the stability and matrices of rock, in this particular case, schist (Yavuz et al. 2010). As the stone is repeatedly exposed to high temperatures, its durability and structural components begin to deteriorate. This deterioration can be measured and compared to pre-fired physical properties. One of these physical properties is the stones’ porosity, which is calculated using the measured absorption rate of stone before and after exposure to firing episodes. These firing episodes are meant to approximate the cultural use of these stones during prehistoric cooking episodes. The results of the experiment show that FAR may have some diagnostic capabilities to infer multiple firing episodes, confirm facility reuse, and support suggested mobility with respect to available resources and temporal episodes through accelerator mass spectrometry (AMS) dating and other analyses such as micro-botanical analysis.