310 



THE WONDERS OF GEOLOGY. Lect. IV. 



stones with numerous flint nodules, and cretaceous fossils ; 

 and these imperceptibly blend with the pure white chalk at 

 the bottom. These strata are well shown on the banks of 

 the Meuse, and fossils may be obtained in abundance from 

 the extensive quarries, which have been worked for ages. 

 St. Peter's Mountain, in which these excavations are 

 situated, is a cape or headland between the Meuse and 

 the Jaar, formed by the extremity of a range of hills which 

 bounds the western side of the river valley. The moun- 

 tain commences at the distance of a mile south of Maes- 

 tricht, and extends in a direction towards Liege for about 

 three leagues ; it presents an almost perpendicular escarp- 

 ment towards the Meuse. A section of the hill affords the 

 following succession of strata : — 



1 . Lowermost : White chalk, with layers of flint nodules. 



2. Chalk, very hard and gritty. 



3. Calcareous freestone, and beds of loosely aggregated 

 sand, of a yellow fawn colour, abounding in fossils. Nume- 

 rous layers of flint occur throughout the entire series, 

 having the usual characters of the siliceous nodules of the 

 chalk. 



The Maestricht freestone is so extremely soft in the 

 quarry, that it may easily be cut with a knife, but it 

 hardens and becomes of a lighter colour by exposure to the 

 air.* The beds of limestone have a total thickness of 

 about 500 feet. Excavations have for centuries been 

 carried on in the strata of freestone, and from the immense 

 quantities of stone removed, extensive caverns and galleries 

 now traverse the heart of the mountain. Shells, corals, 



* The avidity of collectors has induced the quarrymen to practise 

 an ingenious fraud upon strangers : teeth and bones of the horse, boar, 

 &c. are carefully imbedded in blocks of the limestone while it is soft j 

 and when the stone becomes hard, the specimens are offered for sale as 

 genuine fossils from the quarries ; the deception may be detected by 

 immersing them in water. 



