UNUSUAL ARRANGEMENT OF STRATA. QQ\ 



lu horizontal strata: and what we know of the laws of gra- selves horizon- 

 vitation does not allow us to conceive the possibility of a u y ' 

 precipitate, the particles of which are not yet held toge- 

 ther by the force of cohesion, supporting itfclf in vertical, 

 or even inclined strata. Yet this position exists in many Strata not so. 

 portions of the Earth, particularly those of a certain age. 



It was natural, that various hypotheses should be formed, 

 to account for such a singular fact. The opinion that ap- 

 pears best founded, and most generally adopted, is that of 

 the sinking in of certain parts of the Earth. I do not mean 

 to controvert an hypothesis adopted by many learned men, 

 but I shall submit to them a circumstance, which I cannot 

 explain. 



The Ourthe, which flows through the department of thats ome ; n dl ff e<t 

 name, and that of the Sambre and Meuse, traverses a nar- rent parts of 

 row valley, bordered by lofty hills, several of which are rance * 

 perpendicular. The mineral strata that compose these hills 

 are all more or less inclined, and sometimes in a direction 

 different from that of the valley. This takes place parti- 

 cularly at Durbuy, a small town in the third circle of the 

 department, where the hill is formed of a blueish bitumi- 

 niferous carbonate of lime, that constitutes several systems 

 of strata. One of these systems is cut by a perpendicular Remarkable 

 plane, so that the remarkable arrangement of its strata is one * 

 easily seen. See Plate VII, tig. 4. They have an inclina- 

 tion of about 60° or 30°, and are placed one upon another, 

 like a series of pairs of rafters laid one upon another. The 

 visible part of the first stratum in the centre exhibits 

 only the shape of a wedge. On the top and sides of this 

 stratum is placed a second, the summit of which is equally 

 cuneiform; while the sides, sloping like those of a roof, 

 cover the first wedge. Thus they continue in succession to 

 the top of the hill. But the hill has been flattened by 

 some cause or other, and the last strata have not the same 

 summit as the rest, as they are merely applied on each side 

 of the preceding, sloping in different directions, but not 

 united at the top *. 



What 



* It is very probable, that, if the uppe mrface of the hill were ex- 

 amined attentively, the exterior strata wo Id be found to unite in their 

 V - 1 prolongation, 



