“…A sample of radioelement-free, nonirradiated bitumen (Nash Scar Quarry A) was taken from a vein in the Llandovery Nash Scar Limestone of Powys, Wales, at Nash Scar Quarry. A sample of thoriferous bitumen (Nash Scar Quarry B) was also taken from the underlying Folly Sandstone at this site (Parnell and Eakin, 1989 References are as follows: 1, Parnell (1985); 2, Parnell and Eakin (1989); 3, Haggan et al (2002); 4, Kelley and Kerr (1958); 5, Radcliff (1906); 5, Davidson and Bowie (1951); 7, Eakin (1989); 8, Parnell (1988); 9, Aminoff (1943); 10, Grip and Ö dman (1944); 11, Landais et al (1993); 12, Leventhal et al (1987); 13, Kríbek et al (1999);14, Welin (1966). a Not detected (See Section 2.1 for discussion).…”