Miss M. S. Johnston — Geological Notes on Central France. 59> 



about 6x6x2 feet. The surfaces of these two large slabs bave 

 been deeply scored by ruiiuing water, and pierced in all directions 

 by rootlet and other holes. — C. D. S. -• 



1896. In the Proc. Geol. Assoc, vol. xiv, p. 158, Mr. Alien 

 Brown states that " a large tabular water- worn Sarsen, and a portion 

 of it broken off in Quaternary times," were found in the gravel at 

 Hanwell ; and that another Sarsen occurred at the base of the 

 gravel at the back of Hanwell Station. 



1900. In " The Pits," old gravel workings, an allotment, now- 

 wooded, belonging to William Sherborn, Esq., and formerly part of 

 Bedford Common, Middlesex, there is a large Sarsen, measuring 

 about 5x5x2 feet, from one end of which a block about a foot 

 thick was removed. — C. D. S. 



1900. In front of the roadside inn (the " GrifEn ") at Totteridga 

 or Whetstone, near Highgate, stands a short thick Sarsen, abuut 

 25 inches high above ground, and 20 inches broad at top and 

 18 inches below. It is locally said to be as large again below th© 

 surface ; and to have been used as a ' whetstone ' for their weapons 

 by the soldiers going to the Battle of Barnet (1471). — A. 0. Brown. 



1900. Horace B. Woodward describes a Greywether from the 

 Gravel of South Kensington, in the Geol. Mag., December, 1900^ 

 p. 543 (with figure). It measures 3 ft. 10 ins. X 3 ft. 3 ins. X 2 ft., 

 and is in many respects analogous to the specimen from Bayswater 

 described above. A smaller one has just been found on the same 

 spot (January 23, 1901). 



[To bt continued.) 



IV. — SoMK Geological Notes on Central Feance. 



By M. S. Johnston. 

 (PLATES II-IY.) 



1 THOUGHT, perhaps, some readers of the Geological Magazine 

 might be interested in a few notes taken during the Inter- 

 national Geological Congress excursion to the Massif of Central 

 France and the region of the Gausses, and on the chief rocks there, 

 with the best places for finding examples. 



- By making Clermont Ferrand a starting-point, the Piiy de Dome 

 may be visited first. The road winds its way up from the extensive 

 plain of Limagne. This plain, of Teitiary age, extends all along the 

 foot of the Monts Domes from Brioude to the Loire. It is formed 

 by an alluvial deposit left by an ancient lake of the age of the Paris 

 Basin, whose waters at periods of high level probably flowed into 

 Lac Limagne. The Monts Domes rise abruptly from this plain, 

 their basalt flows forming in places preci})itous cliffs. 



At Royat, the great basalt flow of Quaternary age is reached, at 

 the foot of which abundant mineral springs gush out. On either 

 side of the lava rise rounded hills of granite; the typical granite 

 of these hills is grey and coarsely crystalline. 



The Pay de Dome is composed of tracliyte. The typical rock 

 contains large crystals of sanidine, and is very acid, having G2 per 

 cent, of silica. M. Michol-Luvy is of opinion that the trachyte is- 



