of the Environs of Tarts . 3 7 



found in very distant countries, are scattered in the strata 

 nearest the surface: a strongly- marked character of a great 

 eruption proceeding from the south-east is imprinted on 

 the forms of the eminences and the directions of the val- 

 leys : in short, there is no district better adapted for making 

 us acquainted with the final revolutions which put a ter- 

 mination to the formation of our continent. 



This country has nevertheless been very little studied 

 under this point of view ; and although so long inhabited^ 

 by many enlightened men, whatever has been written on 

 the subject has been confined io some detached fragments, 

 and ahnost all of them are either exchisively mineralogical, 

 without any regard to organized fossils, or purely geologi- 

 cal, without reference to the position of these fossils. 



A memoir of Lamanon, on the gypsums and their 

 fossil bones, may perhaps form the only exception to this 

 classification : we are bound, however, to acknowledge that 

 the excellent description of Montmartre by M. Desmarets, 

 the information given by the same author as to the basin 

 of the Seine, in the Encyclopcdie Mcthodique, the mi- 

 neralogical essay on the department of Paris by M. Gillet- 

 Laumont, the extensive researches on the fossil shells of 

 theenvirons of Paris by M. Lamarck, and the geological 

 description of the same district by M. Coupe, have been 

 advantageously consulted, and have several times directed 

 our steps. 



We presume to think that the task of which we are about 

 to present the class with a sketch, will not be without in- 

 terest, notwithstanding the works above alluded to. 



Four years ago we commenced our labours; and although 

 we have persevered in them by making numerous excur- 

 sions, collecting specimens and information from every 

 quarter, we are far from thinking we have done enough, 

 and we earnestly desire that our readers may not confound 

 the abridgement which we are about to give, with the full 

 details which we propose to publish. Some circumstances 

 compel us to present this abridgement at this moment, and 

 to assign a date* to such tedious and laborious researches, 

 before the happy period at which we shall think them 

 brought to a conclusion. 



From the nature of their object, our sketches were li- 

 mited according to the nature of the soil, and not according 

 to arbitrary divisions. 



We thought it right therefore, in the first place, to de- 



* Thi» Memoir was printed in Jan. 1809. — Edit. 



C 3 termine 



