Jui-v 0, 1S83.] 



SCIENCE. 



15 



ami of detail which is scattered in the numer- 

 ous papers of the Belgian geologists. Any 

 one of ordinary intellectual culture, and inter- 

 ested in Belgium, will find it a dear and read- 

 able account of the past history and chief 

 features of the eountr\'. Two causes have 

 contributed to make easier the task of the 

 author : tiie works on the geology of Belgium 

 by d'Onialius, Dewalque. and especially the 

 celebrated " Esquisses geologiqucs ' of Gosselet, 

 have already pointed out the way to success ; 

 and. moreover, the natural disposition of the 

 country allows a very simple grouping of facts. 



Both geologically and geographicall}', Bel- 

 gium is formed of two distinct parts. The 

 southern half (the Ardennes) is a hilh" region, 

 a continuation of the old paleozoic nucleus of 

 Europe, — the so-called Ilercynian mountain- 

 range ; the northern half (Flandres, etc.) is a 

 flat land or prairie region, and forms part of 

 the great plain of northern Europe, the basin 

 of the North Sea. The Ardennes is a paleo- 

 zoic district ; Flandres, a tertiary one ; the 

 triassic, Jurassic, and cretaceous formations 

 forming but a broken belt around the paleo- 

 zoic masses. All these formations are, how- 

 ever, studied by the author in a complete 

 manner, and their mineralogical, paleontologi- 

 cal, and stratigraphical characters successively 

 described. Both their historical divisions and 

 their local extension are given with care. 



Beginning with the older rocks, we first meet 

 the Cambrian shales, forming two principal 

 ranges (massifs de Hocroy and de Stavelot). 

 These rocks can be compared to the Ocoe 

 conglomerates and shales of the Appalachian 

 region ; they contain the curious interbedded 

 crystalline porphyroids, so well illustrated bj' 

 de la Valine Poussin and Kenard, whose papers 

 are here summarized in two good plates. The 

 Silurian beds form two small crests extending 

 east and west, through Brabant and Condros. 

 and have supplied fossils of Barrande's second 

 fauna. These beds, like the underljnng Cam- 

 brian, have a southerly dip. The upper Silu- 

 rian fauna is not represented. 



The folding of the Silurian rocks was the 

 initial cause of the so-called Dinant and 

 Namur devono-carboniferous depressions, or 

 basins. It was followed )\v a long-continued 

 depression of the area, in consequence of 

 which the accumulation of an enormous thick- 

 ness of stratified rocks within the great troughs 

 of Dinant and of Namur took place. This 

 downward bending of the earth's crust did 

 not go on continuously, but submitted to some 

 irregularities related to the breaks and numer- 

 ous stratigraphical divisions of the Devonian 



formation. The Devonian formation of Ar- 

 dennes is the most complete and best studied 

 in Europe, through the labors of Dumont, 

 Closselet, Dupont, and the author. It shows 

 a thick series of four thousand metres of 

 alternating fossiliferous shales, sandstones, 

 and limestones, marine for the chief part, 

 though some beds have furnished Psilophyton 

 and other plant-remains. After the period of 

 the mountain limestone, littoral, brackish' 

 water, and finally lacustrine and terrestrisil 

 deposits, came in, and the coal continued 

 forming. 



A general movement of elevation succeeded 

 towards the end of the coal-measures, and 

 folded all the paleozoic sediments as if they 

 had been crushed from south to uorth. This 

 thrust had a more violent efiTect in the Namur 

 than in the Dinant basin. In the former are 

 comprised the celebrated coal-fields of Mons, 

 Liege, and Charleroy, — the chief causes of 

 J5elgian prosperity and wealth. 



At the close of the paleozoic period, the 

 mountainous region of southern Belgium was 

 formed ; and since then it has always been 

 exposed to denudation. South of this moun- 

 tainous district, the .Jura-triassic beds of east- 

 ern France now began to accumulate in the 

 (iulf of Luxemburg (Buntersandstein and Keu- 

 l)er, and the Jurassic from the A\'icula contorta 

 l)eds to the middle oolites). These mesozoic 

 seas did not penetrate north of the Ardennes, 

 where the lower cretaceous are the most an- 

 cient mesozoic formations. 



The cretaceous formations in this district 

 possess great interest, notwithstanding their 

 small geographical extent. The lower beds 

 have furnished the splendid iguanodons of 

 the Brussels museum, and the upper ones 

 are the well-known Maestricht beds. All .ire 

 chiefly littoral formations ; and the so-called 

 tourtias of the middle cretaceous are famous 

 bv the variety and richness of their faunas. 

 In the deep and narrow Oulf of Mons, the cre- 

 taceous beds are found in a chalky condition, 

 as in the Anglo-French basins. 



In the neighborhood of Mons and Landen are 

 found the most ancient representatives known 

 in Europe of the tertiary epoch (systeraes mon- 

 tien, heersien). so well illustrated by Cornet 

 and Briart. The Landenian 8\-stem has a 

 wider extension, forming, with the other terms 

 of the eocene series, nearly all of lower Bel- 

 gium. "Thus it is to the wide-spread mass of 

 the London clay, wiiich covers the Landenian 

 sands, that Belgium owes its meadows and 

 well-cultivated fields, which extend in an im- 

 mense plain from the Brabant to the coast. 



