110 STEVENSON— FORMATION OF COAL BEDS. [Apdl 21. 



The first type is that of the Hainaut coal basin in Belgium, a 

 small area, 15 kilometers wide and separated from the Campine basin 

 at the northwest by 60 kilometers of older rocks, while on the south- 

 east it is bounded by a fault. The fossils show that, at times, this 

 basin communicated with the sea. The deposits are thin at the 

 north, where the beds have remained unaiTected by subsecjuent dis- 

 turbance ; but they thicken to 3 kilometers toward the southerly 

 border of the basin, where the disturbance increases as the fault is 

 approached, the downthrow having caused close folding. The hinge 

 of movement was near the southeast bounding fault. If the peat 

 bogs were formed at the unvarying sea-level, the first of them should 

 have had, when the basin was filled, an inclination of 25 cm. per 

 meter and the last should be almost at sea-level, while the inter- 

 mediary beds should converge toward the shore line at the north- 

 west. The conditions being absent, it is evident from this mathe- 

 matical demonstration that the coal beds are not buried peat bogs. 

 The warning against the dangers of dependence on palaeontology 

 is repeated, and the necessity for the warning is proved by the dis- 

 covery of the Bernissart iguanodons in rocks other than those to 

 which the animals belonged, as well as by the possibility that some 

 day remains of fossil man may be discovered under a landslide from 

 a chalk cliff. 



The second illustration is that of an area, increasing in extent 

 as it deepens. There, convergence of the beds toward the hinge 

 of movement would not be a criterion. The upper beds should be 

 of greater extent than the lower. This is to explain conditions 

 existing in the Appalachian basin, where one thick coal bed, the 

 Pittsburgh, has an area e(|uivalent to not less than 400 kilometers 

 scjuare. It is difficult to understand how materials from the anti- 

 clinal borders could reach the central parts of such a synclinal to 

 give parallel beds there. In the central parts of the basin are great 

 masses of red shale and beds of limestone and tlie coal beds are not 

 rigorously parallel. 1 le is inclined to think that the materials within 

 the central parts are due to precipitation ( from solution ) without 

 mechanical trans])orlation from the borders. ( )ne cannot assert 



110 



