I only became aware of the existence of Radyr Quarry thanks to to three bryophyte records made by A.E.Wade in 1950. Despite being close to home the quarry is completely hidden in trees and scrub, and doesn't stand out on my Explorer OS Map. After a bit of online research I discovered it was quarried for Radyr Stone from the 1800s until around 1920, after which it was used as a refuse tip.
Yesterday lunchtime I visited the southern end of the quarry (ST139794) and was pleasantly surprised by the diversity of bryophytes on the very shady rock faces. Radyr Stone is a breccia, comprising Triassic red sandstone with embedded fragments of Carboniferous Limestone. Given this one would expect the flora to be calcicolous, and this proved to be the case. A single large tufaceous patch was covered in Eucladium verticillatum (photo below).
Not far away there were several patches of Leiocolea turbinata on soil-capped ledges (photo below), a new species for me. I think both this species and the Eucladium are new for ST17.
The quarry extends a fair way to the north, where it can be accessed via a LNR in Radyr (probably easier than the scramble through brambles at the southern end). I'll certainly check out the rest of it at some stage.
Incidentally, the three species Wade recorded were Riccardia chamedryfolia, Tortula modica and Microbryum davallianum. There is probably no suitable habitat remaining for the latter two species, which shows how much the quarry has changed in the last 65 years.