An unusual occurrence of a well-defined playa scraper and furrow in a small playa-like area was observed near McKittrick, California. A 20-foot fill, made during construction of California Highway 30, blocked a broad drainage channel in the low hills

End_Page 482------------------------------

south of McKittrick. Small, flat, mud-cracked clay surfaces much like the familiar desert dry lakes developed on either side of the highway fill. The playa-like area east of the highway, where the occurrence was noted, is approximately 230 feet wide and 300 feet long.

The playa scraper, which was part of the fill material, is a crudely ellipsoidal boulder of quartz conglomerate weighing about 175 pounds. Movement was from close to the fill embankment along a slightly arcuate path for a distance of 99.2 feet toward the outer margin of the dense clay surface. The playa furrow developed on the still-moist surface is 20 inches wide, its edges having been raised ½ inch above the level of the surrounding area. Depth of the trail increased from 2 inches at the starting point to 2½ inches at the terminus. Mud pushed by the moving boulder was left as a low mound of dry clay in front of the scraper.

Movement of the scraper by wind does not seem to be a feasible explanation. Not only is the area sheltered from air currents, but the direction of movement is nearly at right angles to, and away from, the protective embankment. Transportation by ice floes is equally difficult to defend because the McKittrick area is one of rare freezes and it is doubtful that, even if freezing did occur, the thickness of ice formed would be sufficient to move a 175-pound boulder. Hydraulic action promoted by a drain beneath the fill is suggested as the possible motivating force for the McKittrick scraper. A similar occurrence at the Racetrack Playa in Death Valley, California, supports this supposition.

End_of_Article - Last_Page 483------------