Tim Daw / compiled 2 September 2026. CC BY-SA 2026 Tim Daw.
Graded silcrete / sarsen localities from Isaac, Gallois, Bristow, Nash and the Devon HER — not folklore. Nash 2020 sampled only Mutter’s Moor 1 and 2; not a Devon survey.
Circles are Devon records, coloured by confidence. Dashed squares are Somerset analogues — real silcrete, wrong county. Rejected pins (quartz menhirs, Flitton sandstone, Woolley Grit) stay on the map so the comparison is visible.
Sandy silcrete is classic sarsen: palaeogene quartz sand cemented by silica. Flint breccia is the local puddingstone analogue — angular chalk flints in a siliceous matrix, not Hertfordshire rounded puddingstone. Chert duricrust is Bristow’s west-Bovey silcrete/ferricrete growing on Palaeozoic radiolarian chert. Basin sandstone is the Woolley Grit, an in situ chalcedonic member of the Bovey Formation — related silica mobility, not a Chalk-plateau sarsen train. Vein quartz and sandstone on this map are rejected as sarsen. Residual flint gravels (Haldon, Tower Wood) are not sarsen either.
Nash, Ciborowski, Ullyott, Parker Pearson, Darvill, Greaney, Maniatis & Whitaker, 2020, Science Advances 6, eabc0133, sampled boulders in 20 representative areas of sarsen concentration from Devon to Norfolk. They did not run a Devon survey. Conglomeratic silcrete (“puddingstone”) was deliberately not sampled. The two Devon sites are Mutter’s Moor 1 and 2 (their nos. 7–8). Exact 8- or 10-figure pins were not printed in the open paper or in Data File S1; the working envelope is Isaac’s Mutters Moor type stream section SY 1055 8789. Staple Fitzpaine is an analogue photograph, not a Nash sample. Valley of the Stones 1 and 2 are sites 9–10, Dorset.
Tim Daw’s 18-row sheet is the starting list, not ingested uncritically. The Rolling Stone northing 921x is about 4 km south of Putts Corner; the pin used is the HER current site SY 1459 9620 (original SY 1461 9621). Isaac 1979, not 1981, is the Sidmouth type-section paper. Shebbear sits on BGS sheets 307/308, not Chulmleigh 309. North Molton church is MDV765 (Flitton sandstone), not MDV388. Yarty is not a Nash sample. Britrocks has no Devon sarsen/silcrete specimen; Woolley E-series numbers are basin sandstone. Seven Stones, Haldon and North Molton are graded down. Whitestone, Lee Downs and the Damage Barton alignment are kept as rejected quartz so they can be compared with the silcrete records. Sites added from the papers: Mutters Moor type, Salcombe Hill breccia megaliths, Ringslade, Higher Brimley, Ramshorn, Woolley Grit, Staple Fitzpaine and Combe Beacon.
Gallois 2009: blocks of Tertiary silcrete (sarsens) are relatively common on the Clay-with-flints of the East Devon plateau; none were seen in situ, and none are gridded as individuals. That lag population is certain; it is the scientific basis for “Devon is littered with sarsens, mainly in the south.” It is not given a map pin here.