1018 REPORT—1885. 
2. On the Re-discovery of lost Numidian Marbles in Algeria and Tunis. 
By Lieut.-Colonel R. L. Piayvarr. 
The author explained that the name itself was a misnomer, as they are not 
found within the limits of Numidia proper, but in the province of Africa and in 
Mauritania. Most of the ‘Giallo antico’ used in Rome was obtained from Svmattu 
Colonia, the modern Chemtou, in the valley of the Medjerda, the quarries of which 
are now being extensively worked by a Belgian company ; but the most remarkable 
and valuable marbles are found near Kleber, in the province of Oran, in Algeria. 
There, on the top of the Montagne Grise, exists an elevated plateau, 1,500 acres in 
extent, forming an uninterrupted mass of the most splendid marbles and breccias 
which the world contains. Their variety is as extraordinary as their beauty. 
There is creamy white, like ivory; rose colour, like coral; Giallo antico; some are as 
variegated as a peacock’s plumage ; and on the west side of the mountain, where 
there has been a great earth-movement, the rock has been broken up and re- 
cemented together, forming a variety of breccias of the most extraordinary 
richness and beauty. 
Colonel Playfair exhibited specimens of the principal varieties, to prove that 
his descriptions were not exaggerated. The beauty of these marbles has been 
recognised by the trustees of the British Museum, who are now mounting the 
sculptures of the Parthenon and the Mausoleum on basements of them. Specimens 
may also be seen in the Mineralogical Room of the British Museum, at South 
Kensington. 
The marble mountain belongs to Signor del Monte, of Oran, and, although it is 
not being worked as it ought to be, blocks can be obtained at a cost of about 181. 
per cubic métre, ready for shipment. ; 
3. Second Report on the Rate of Erosion of the Sea Coasts of England and 
Wales.—See Reports, p. 404. 
4. The Chasm called the Black Rock of Kiltearn. By Witu1am Watson. 
This is a narrow ravine in conglomerate: its length is about 14 mile; its depth 
varies from 100 to 130 feet ; its breadth at the top varies from 12 or 15 to about 
30 feet. The river which flows through the ravine is the Altl-Granda; it drains 
Glen Glass (above the ravine) ; the water flows into Cromarty Firth. 
The author refers to popular views held to explain the formation of the ravine 
—earthquakes and fracture, and shows that these are inadequate. The ravine has 
clearly been produced by erosion, of which the marks are still visible on the sides ; 
the difficulty is to explain how erosion could have produced a gorge of this kind 
without weathering action and floods having denuded the sides. 
Above the gorge in Glen Glass was once a lake. This had been silted up to 
the height of about 80 feet with sand, washed out of the Glacial débris of the glen. 
When the barrier that confined the lake gave way the river flowed over the surface 
of the conglomerate, carrying with it much sand from the lake-silt, and using this 
as a means of rapidly eroding the rock. When the chasm was deep enough to 
prevent the floods from overflowing the banks the sides could not be widened to 
any great extent. The disproportion between the deepening and widening process 
has been maintained, thus causing the steep-sided narrow glen. The excavation 
now going on is small, whilst the weather has some effect on the sides; so that 
ultimately an ordinary valley will be produced. 
5. The Bass of Inverurie, a fragment of an ancient Alluvial Bed. 
By the Rev. Joun Davipson, D.D. 
The Bass of Inverurie, a green conical hill about 50 feet high and singularly 
symmetrical, stands isolated in a corner of the united river valleys of the Don and 
Ury, which latter stream washes its base. 
