M. de la Jonkaire on the Geology of Antwerp. 97 



in consequence of recent discoveries, one of the characteristic 

 minerals of the plastic clay, and which has been collected in 

 Holland at a very remote period, and since at different times 

 in the bituminous beds, to which the authoi's who mention 

 these discoveries assign in general the name of peat. These 

 beds form, without doubt, the continuation of the bituminous 

 beds of Low Germany, where M. Coquebert de Montbret and 

 others have also observed amber, and are consequently lig- 

 nites. 



*' If therefore true plastic clay exists in the same basin, in 

 places in the vicinity, and in a similar position ; and if beds 

 possessing the mineral character of this rock are found at 

 Antwerp, — it appears to us, that the latter can only be refer- 

 red to the clay formation ( plastic clay ) beneath the calcaire 

 grossier of Paris. 



" Shelly Sands.— These resting upon the above would there- 

 fore, according to our opinion, represent the calcaire grossier. 

 This we shall endeavour to establish. 



" We should remind the reader in the first place, how de- 

 ceptive is the apparent nature of a rock, when employed as a 

 character in determining a formation ; and that notwithstand- 

 ing these sands may not afford true calcair-e grossier to the 

 mineralogist, they may so to the geologist. A greater diffi- 

 culty exists in the perfect resemblance of its fossils to those of 

 Italian tertiary rocks, at present regarded by many authors 

 as above the Paris gypsum. At Antwerp, as in Italy, bones 

 of Cetacea are found ; the shells are of the same species, and 

 there exists no well marked difference between the two places : 

 yet we cannot, notwithstanding this analogy, consider the 

 rocks of Antwerp as referable to the second marine formation 

 of Paris. The sharks* teeth, so frequently found at Antwerp, 

 are common in calcaire grossier ; whether those of the genus 

 Scilliuvi, or those of the genus Carcharias. The Nummulites 

 and Turbinolites found at Ghent in the same sands, resemble 

 those of the calcaire grossier. Burtin has given, as coming 

 from the same beds as at Antwerp, Voluta Harpula, Voluta 

 Cythyra^ Hippocrenes, and perhaps Cerithiurn Gigas, a fossil 

 so essentially characteristic of the lower marine formation. 

 Lastly, and this appeal's to us the most important fact, nearly 

 a fifth part of the bed we are describing is composed of sili- 

 cate of iron. This, we say, is very important; in fact the 

 lowest beds of the Paris calcaire grossier are so highly charged 

 with it as to pulverize entirely; while a mechanical analysis 

 which we have made of the second marine formation of «.hf- 

 fercnt places, has never afforded us a single grain of this sub- 

 stance." 



iV^wSmw. Vol. 2. No. 8. y%. 1827. O The 



