Discussion of Jamaican Cenozoic ichnology: review and prospectus: (v. 50, pp. 364–382) SIMON F. MITCHELL 1 * and RYAN RAMSOOK 2 1 The University of the West Indies, Kingston, Jamaica 2 Trinity Exploration and Production Plc., San Fernando, Trinidad and Tobago We make two comments on the paper ‘Jamaican Cenozoic ichnology: review and prospectus’ by Donovan et al. (2015). Based on biostratig- raphy and new radiometric dates, we recommend the separation of the Richmond Formation (deposited in the Wagwater Graben and onlapping onto the edges of the Clarendon Block and Blue Mountains Block) and the Moore Town Formation (deposited in the John Crow Mountain Graben) which are of early Eocene and early Paleocene age, respectively. The ichnofossils of the Scolicia ichnocoenesis are differ- ent in the two basins. We also point out that extensive borings recorded from the late Eocene Somerset Formation of the White Limestone Group most probably came from the late Oligocene Walderston Formation. Copyright © 2015 John Wiley & Sons, Ltd. Received 4 February 2015; accepted 17 February 2015 KEY WORDS ichnofossils; Richmond Formation; Moore Town Formation; White Limestone; Jamaica 1. INTRODUCTION We read the paper by Donovan et al. (2015) with great inter- est, as it represents a very useful summary of the ichnology of Jamaica. However, we feel the audience for the paper would benefit from some discussion and the correction of a probable stratigraphic error. 2. THE PALEOGENE ‘RICHMOND FORMATION’ ICHNOFOSSILS We understand why Donovan et al. (2015) have continued to use the name Richmond Formation for the deep-water siliciclastic units in both the Wagwater and John Crow Mountains belts based on similar lithology; however, our recent work confirms previous suggestions that they should be treated as different lithostratigraphic units. During the last 10 years, nearly the complete outcrop of these rocks has been mapped by us in the preparation of a new series of 1:50,000 scale geological maps (e.g., Mitchell, 2015). Part of this work has recognized that the Blue Mountains represent a flower structure that developed progressively during the late Cenozoic (James-Williamson et al., 2014). We interpret the fault (Rio Grande Fault) that separates the John Crow Mountains Belt from the Blue Mountain Block as a terrain boundary separating very different suc- cessions. To the east of the Rio Grande Fault, the succes- sion consists of the Bowden Pen Formation, Moore Town Formation (Richmond Formation of Donovan et al., 2015) and Nonsuch Formation (Jiang and Robinson, 1987). Various studies have dated the Moore Town Forma- tion as early Paleocene: nannofossil zones NP2-NP4 and planktic foraminifer zones P1c-P2 and the overlying Nonsuch Formation as NP5-7 and P3b (Jiang and Robinson, 1987; Robinson and Jiang, 1990; Fluegeman, 2002, 2004). To the west of the Rio Grande Fault, the succession shows a typical steer’s head basin configuration (White and McKenzie, 1988) with synrift conglomerates (Wagwater Group) concentrated in the Wagwater Graben (now Wagwater Belt) during tectonic-driven subsidence followed by subsequent onlap of post-rift limestones and mudstones (Richmond Formation) onto the Blue Mountains and Clarendon blocks during a transition to thermal subsidence. The conglomerates of the Wagwater Group contain one prominent flooding event (the Pencar River Member of Mann and Burke, 1990) which has yielded a late Paleocene NP9-10 nannofossil age from Clydesdale and Catherine’s Peak (Jiang and Robinson, 1987). Rhyodacite Jamaica-type adakites in the upper part of the Wagwater Formation give *Correspondence to: S. F. Mitchell, Department of Geography and Geol- ogy, The University of the West Indies, Kingston 7, Jamaica. E-mail: simon.mitchell@uwimona.edu.jm Copyright © 2015 John Wiley & Sons, Ltd. GEOLOGICAL JOURNAL Geol. J. (2015) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/gj.2675