Western Mono consultants identified three functional types of BRMs (starter, finishing, and seed mortars) at BRM sites at Crane Valley in the central Sierra Nevada. McCarthy et al. (1985) found these categories to be statistically significant and concluded that variability in mortar depth could be related to functional differences. Western Mono consultants also indicated that the high frequency of starter mortars across the landscape reflects the ease of manufacturing shallow mortars (H. McCarthy, personal communication 1991). Acorns could be processed without finishing mortars, although starter and finishing mortars were used at locations where acorns were processed in large quantities over a longer period of time. In this paper the categories of mortar types among the Western Mono will be applied to data from Mono County after an examination of archaeological evidence regarding milling tool use in the eastern Sierra Nevada.