Sedimentary features associated with the sandstone interbeds on Highlands.

(A) Horizontally laminated sandstone interbed unit overlying the basalt with a sandstone-filled fissure and a sharp but non-erosional contact. (B) Ropy-surface texture of pahoehoe lava flows preserved as a natural cast on the underside of a massive sandstone bed. These casts of the ropy-basalt surface suggest that the deposition of the sandstone interbeds occurred in non-erosive, and possibly rapid sedimentation events. (C) Casts of fine desiccation cracks and interference ripple marks (in the inset). (D) Casts of coarse desiccation cracks. (E) Large-scale trough cross-bedding in a 40-cm-thick medium-grained sandstone layer. (F) Planar cross-bedding with tangential, moderately inclined foresets in a ~ 120-cm-thick medium- to fine-grained sandstone layer. (G) Side-view of the track-bearing massive sandstone layer and underlying horizontally laminated sandstone bed. (H) Close-up of portion of G. Abbreviations: Sh–horizontally laminated sandstone; Sm–massive sandstone; Sr–ripple marks or ripple cross-laminated sandstone; St–trough cross-bedded sandstone; Sp–planar cross-bedded sandstone; Ds–desiccation cracks.