Thank you for submitting your item for appraisal. This appears to be a pair of ink and watercolour drawings by Elmer Ginzel Plummer (American, 1910 - 1987). Plummer apparently lived in the Los Angeles area and worked as a studio artist for Walt Disney and Warner Bros. in the 1930's. Few of his drawings have been offered or sold at auction. The drawings in your possession are most likely dating to the 1970s or later and might depict trees in one of California´s national parks. The estimate is based on the few auction listings and drawings of similar quality by lesser known artist sold at auction.