South West Scotland Group: Dob’s Linn, Upper Moffatdale

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24 July 2022 (10:00 - 17:00)

The recording group having lunch at Dob's Linn, left to right, Bob Merritt, David Long, Phil Lusby, Gordon Rothero, Valerie Heppel, Chris Miles

Meeting report

Dob’s Linn is named after the Covenanter Halbert Dobson, who is believed to have successfully hidden from his English pursuers in a cave near the waterfall for several weeks in the 1690s. This site in upper Moffatdale is near the boundary between VC72 Dumfriesshire and VC 78 Selkirkshire, and is a site that both David Long and Liz Kungu have wanted to survey for bryophytes because of both the complex geology and topography. It is a ravine between 290 and 370 m a.s.l. in the Moffat Hills, famous for the immense variety and concentration of graptolites that amateur geologist Charles Lapworth first used to age the different rock strata. The Silurian Gala Greywackes are underlain by the Upper Ordovician/Lower Silurian Moffat Shale Group, and both strata have been subjected to extensive folding. The end result is a geologically complex site with very loose, friable, acidic and base rich rocks in close proximity and many areas of steep scree and contorted rock outcrops.

After the preceding week’s heatwave, it was something of a relief to meet on a day with a gentle smirr, and the preceding night’s rain meant there was no need for spray bottles. We parked in the monad NT1915, which we spent most of the day recording. On the way down to the Moffat Water, the lower reaches of Raking Gill produced the first of many star finds for the day. David collected a Hygrohypnum, which was subsequently identified as Platyhypnum (Hygrohypnum) durisculum, a species believed not to have been previously recorded in the Southern Uplands of Scotland. However, during a search of the herbarium at the RBGE, David found a specimen from “near Moffat” collected by C. Howie, in July 1863, so the species is still present after 159 years, as it is probable this could have been the site of the original collection. The recording continued apace, with many indicators of base rich flushing, Palustriella commutata, Tortella tortuosa, close by acid loving species such as Diphyscium foliosum and it took us till lunch time to make our way up the first 300 m of the ravine to the point where the two streams divided. After lunch we continued up the main valley to the spectacular three-tiered Dob’s waterfall at the head of the Linn.  Access along this stretch of the Linn is more difficult, as the sheep track has been washed away, and there are many areas of loose rock, with steep slopes to the water requiring some scrambling to get to the lowest of the waterfalls. On the way, we found a rock outcrop covered in extensive Grimmia atrata, a species for which the Moffat Hills appears to be a Scottish stronghold, along with the Cairngorms. There are six other localities in the Moffat Hills, so it is good to expand the known distribution.

The base of the lowest waterfall had a few interesting additions to the list, including Isopterygiopsis pulchella, Plagiochila punctata and P. spinulosa. Chionoloma cylindrotheca (Oxystegus daldinianus) is only known from one other site in Dumfriesshire, which is also in the Moffat Hills near Hartfell on the Borders Forest Trust reserve at Corehead and Bartramia halleriana, is a recent VC record for VC72, and was last recorded in July 1891 by J. McAndrew at Cornell (Cornal) Burn in the hectad to the south of this one. As the Cornell Burn has subsequently had extensive conifer plantations the species is unlikely to survive in its original location. The rock outcrops below the lowest waterfall had fertile Bryum pseudotriquetrum, which was subsequently identified as var. bimum, not known elsewhere in the D&G region and another VC record for the day. So, although we failed to relocate the Cololejunea calcarea which Milne-Redhead found here by the waterfall in 1962, there were many other exciting species to be recorded.

The waterfall provided an intractable barrier to further progress upstream so after descending from the waterfall, we followed the northern tributary, where Gordon Rothero found Grimmia elongata, the top star find, and another VC record for the day. This species was previously only known from three Scottish VCs, and most of the existing Scottish records come from the Cairngorms in VC 90 and 92. There is a 1957 Alan Crundwell record from Screel Hill in Kirkcudbrightshire, VC 73, but our 2005 meeting there failed to find the species.

After working our way up the northern burn, the weather took a turn for the worse, and so it was decided to climb out of the ravine and make our way back down to the cars, after a very exciting and successful days recording. In total 135 species were recorded for Dob’s Linn, which included 4 VC records for Dumfriesshire. My thanks to NTS for access, and the company of Martin Lyall, the summer reserve warden who came out with us for the day.

Liz Kungu, October 2022