Fig. 3.

Bedding surface views (A–F) and serial thin sections (G–L; perpendicular to bedding, upper bedding surface on top, nonpolarized transmitted light photomicrographs). (A) Clustered, preferentially oriented specimens with no evidence of overlapping or crosscutting. The specimen on the right, whose central axis (ca) is bracketed with arrowheads, is almost perpendicular to preferentially oriented specimens on left. (B) Detail showing two specimens (arrows) that stopped growing because of fast-growing neighbors. (C) Slab with densely packed specimens and thin layer of silts (si). The light color of the central axis and side branches is accentuated by residual silts. (D) Detail of rectangle area in C showing silt layer. (E) Polished thick section of D showing distally terminated side branches (black arrowheads). Under reflected light, light-colored carbonaceous/clay layer is flanked by dark-colored calcispar layers along central axis and side branches. Arrow points to close contact but no crosscut between side branches from two individuals; the contact can be confirmed by tracing at high magnification the carbonaceous/clay layer, which does not continue from one branch to another, and by the observation that the two side branches cannot be traced to the same central axis. (F) Specimen with short side branches (black arrows and arrowheads) and distally dichotomous side branches (white arrowheads). (G–K) Serial thin sections corresponding to labeled lines in F. Pendent vertical walls correspond to distal part of side branch (white arrows) or short side branch (black arrows). The arching vertical wall (arrowheads) is indicative of prior existence of floor. (K) Oblique section of central axis (ca). (L) Detail of I showing pendent vertical wall (arrow) and stylolite. (Scale bars: 1 mm, except where otherwise noted.)