Figure 3 —Bivalve taxonomy at present. Carter (1990) and Campbell et al.'s (1998) schemes are identical except that Campbell et al. remove the pen shells (“Pinnoida”) from the wing-shells (“Pterioida”) and give them equal rank. Prezant (1998) and Coan et al. (2000) have identical taxonomic

and not simply a loose fossil. Scale bar  =  5 mm. C) Concretion nucleated around articulated, delicate pen shell, indicating early diagenetic origin. Scale bar  =  20 mm. D) Concretion with large, articulated endobenthic bivalve nucleus. Scale bar  =  10 mm. E) Concretion with elongated, articulated endobenthic

diameter is 22 mm. B) Quartzite-pebble conglomerate interpreted as a transgression lag deposit. Pebbles and large bioclasts are dispersed in a packstone matrix. Note dense bioperforation of oyster shells (arrowheads). Pencil length is 12 cm. C) Shell breccia facies: concentration of oyster-shell

and shell fragments (yellow boxes); sample 0619-MR-22. C) Sandstone bed with Pelecypod Buchia (yellow arrows) and shell fragments. Pink pen is 14 cm long. D) Sandstone bed with Buchia (yellow arrows); sample 0619-MR-23. E) Dewatering structure in sandstone bed. Pink pen for scale. F) Ophiolitic

; (D) flute casts at the base of a Ngamring turbidite bed (pen for scale). Sedimentary structures in the Padana Formation: (E) pedogenic calcareous concretions; (F) burrows; (G) shell bed; (H) oblique lamination (coin, pen for scale).

Plate 20: Burj Formation (Numayri Member); packstone with abundant shell fragments including trilobites, brachiopods, hyolithids and ovoid Girvanella oncolites, indicated (O). Pen length 135 mm. Wadi Al Hisa, Safi. Photo by J.H. Powell.

such as large one in center, are lumps of CaCO 3 mudstone. Pen is 15 cm long. C . Bed Bed ing surface in oncolitic calcite-cemented sandstone is from same locality as Figure 3 . Oncolites are overgrown on clam shells. Dark streaks at left are shadows. Pen is 15 cm long. D . Cross section of slab

articulate and disarticulate bivalve shells indicative of shallow-marine conditions (Naur Formation) (pen 13 cm long).

is shown in the upper part of the Muwaqqar Formation. (b) The trial mining oil shale operation at Sultani (depth of open pit approximately 20 m). (c) Calcareous concretions (25-30 cm in size) abundant in gastropods. (d) Shell hash of randomly scattered disarticulated bivalve shells (“tempestite

Figure 6 Mesoscale classification of Enriquillo Valley tufas. A) Patch bioherm slab from Cañada Honda West. B) Patch bioherm slab from Cañada Honda. C) Smooth, knobby tufa from the exterior of A). Pen tip for scale. Bioherm components include serpulid aggregations (serp), mollusk shells (mol

trilobite–echinoderm grainstone with thin siliciclastic drapes, Elvinia Zone, ~10.5 m above the base of the section, and ~9.5 m below the base of the Irvingella “ major ” Zone; pen and hammer for scale; note cross-lamination below pen. ( 2 ) Glauconitic trilobite–brachiopod–echinoderm grain- to rudstone

Fig. 9.— Photographs illustrating characteristics of Facies Association 4 at outcrop and in core. A) Bioclastic lag containing disarticulated and fragmented, thin bivalve shells (465.7 m in Iden Green 1; Fig. 5 I). B) Bioclastic lag containing abraded, disarticulated, thick bivalve shells

. Rock hammer for scale. (B) Organic-rich basal lag deposit consisting of abundant coal clasts (c) with scattered granules (g), shell debris, and coarse-grained sandstone. Pen is 8 cm long.

. No detailed lithological subdivision of the Pen-y-lan Mudstone in the core could be located, although it was described by Waters and White (1980) as follows: 312.00–317.39 m ‘Sandstone, grey, fine to very-fine grained, as thin parallel sided beds with numerous thin siltstones and a few thin mudstones

Fig. 3.  Outcrop photographs showing the sedimentological characteristics of some of the most common facies within the Angostura Formation. When present, a lens cap (6.5 cm in diameter), a hammer (30 cm long), and a pen (15 cm long) are used for scale. ( a ) Bedding-plane view of Facies A1

Figure 5. (A) Interstratified bioclastic carbonate and thin-pebble conglomerate in lower few meters of Arroyo de Arce Limestone, southeast subbasin. Lower half of photo consists of silici-clastic conglomerate in uppermost Piedras Rodadas Formation. (B) Transported molluscan shell debris (including

and dendritic textures are clearly truncated and covered by skeletal grainstone and packstone (lower left). B) Enlargement of upper right in Fig. 4A showing pocketlike infilling containing tiny, thin-shelled bivalves, which erodes thrombolite masses (white arrows). C) Thin alternation of skeletal grainstone

for scale. (B) Trough and planar cross-stratified, very coarse grained sandstone of the Kennicott Formation (section 12 in Figs. 3 and 8A ). Disarticulated bivalve shells and shell hash (white) are preferentially preserved in troughs (arrowheads). (C) Tabular sandstones of the Moonshine Creek Formation

near the base of the ACF. (d) Thin hummocky cross-stratified (HCS) sandstone (upper ACF) near the base of the upper ORI. (e) Thick storm bed with coquina shells. Note the cross-stratified set at the top. (f) Laminated organic-rich mudstones, upper ACF, upper ORI. Pen for scale is 14 cm long.