甲· a8。嚣"● ●:∵ 88 B C D 图2-4根据粒级层理确定岩层顶、底面 (据M. P. Billings,) 一水乎岩层,每层自底到顶由粗变细B~正常倾斜岩层,顶面在左上方C一顶面在 右边的直立岩层D-顶面在左下方的倒转岩层 Determination of the top and bottom surfaces from graded bedding AB-normal beds.C- vertical beds. Overturned bedsDetermination of the top and bottom surfaces from graded bedding A, B– normal beds; C– vertical beds; D– overturned beds