508 THE FRESH-WATER LOCHS OF SCOTLAND 
Ordie. — -Partly a rock-basin in schists and partly drift-dammed. 
OssiAN. — Rock-basin in one of the valleys draining the Rannoch Moor 
ice-cauldron. The loch is deepest where two lofty mountains 
approach it on either side, viz. Beinn na Lair (3060 feet) on the 
north and Cairn Dearg (3084 feet) on the south, the surface of the 
lake being 1268 ft. above O.D. 
OwsKEicH. — Vol. n. Part L p. 190. 
P ATTACK. — Partly on rock and partly ponded by drift. 
Peerie Water. — Lying in drift. 
Peppermill. — Artificial reservoir in boulder clay resting on Upper 
Carboniferous strata. 
Phearsain, a'. — Rock-basin in epidiorites and crystalline schists. 
Phitiulais. — In fluvio-glacial deposits, and ponded by alluvium. 
Portmore. — Artificial reservoir in hollow carved out of Silurian grey- 
wackes and shales, partly covered by boulder clay. 
PouLARY. — Narrow valley rock-basin. 
PuNDs Water. — Ponded by drift. 
QuoiCH. — Valley rock-basin in schists, much silted up near the head. Loch 
na Cuilce (Loch of the Reeds) is a small lochan nearly enclosed by 
the delta deposits. 
Rae. — Partly rock-basin in Torridon Sandstone and partly drift-dammed. 
Rannoch. — Vol. H. Part I. p. 137. 
Raoinavat. — Rock-basin in Lewisian Gneiss. 
Raonasgail. — Rock-basin in Lewisian Gneiss. 
Rath, nan. — Kettle-hole in fluvio-glacial deposits of lOO-ft. raised beach. 
Ree. — Partly in Silurian greywackes and partly in drift. 
Rescobie. — One of a chain of small lochs in the open valley of Strath 
More, ponded by glacial gravels lying on Lower Old Red Sand- 
stone strata. 
Roer. — Rock-basin in crystalline schists. 
RosEBERY. — Artificial reservoir in gorge cut in drift and Lower Carbon- 
iferous strata. 
RuATHAiR, AN. — Pondcd by drift. It is situated in the wide open valley 
of Upper Helmsdale, which has been carved out of granulitic schists 
and granite. 
Ruthven. — Rock-basin in crystalline schists on the platform on south- 
east side of Loch Ness (see Loch Bran). 
Sabiston.- — Hollow in drift overlying Middle Old Red flagstones. 
St John's. — Rock-basin in Caithness flagstones of Middle Old Red Sand- 
stone age. At the outlet the water flows across the shattered strata 
along the line of the Brough fault, throwing down the Upper Old 
Red sandstones of Dunnet Head against the flagstones. 
St Margaret's. — ^Artificial loch in Queen's Park, Edinburgh. 
St Mary's. — Ponded by alluvium. The lake lies mostly along the strike 
of Silurian greywackes and is situated in a valley open at the head 
towards Moffatdale. The Moffat Water, by working along a shatter- 
