Figure 7 . Stratigraphy of the northeast wall of Arbitrary Unit 2: a, extending from Arbitrary Unit 1 downhill to the southwest; b, extending from Arbitrary Unit 1 uphill to the northeast. Layers: 1a, plow zone, a mix of black organic silty loam, humus, and underlying clay with sand; 1b, black silty loam with humus, mainly filling soil cracks; 2, gray silty loam with ashy texture and ash lenses; 3a, yellowish-brown to yellowish-gray clay with abundant quartz sand inclusions; 3b, yellowish-brown to yellowish-gray clay with quartz sand, and angular and rounded quartz pea gravel; 4, light gray silty loam with quartz sand and pea gravel, and tabular metamorphic stone pieces (laying horizontally); 5, various colored (bright pink with fine mica inclusions, orange, yellow, and white) marl-like bedrock.