STEATA or THE HAMPSHIEE BASIN. 165 



yi. Subdivisions and Xomeis^clatijee of the Series. 



According to the classification of the Tertiary strata usually fol- 

 lowed in this country, it is necessary to divide the fluvio- marine 

 series into two portions, placing one in the Eocene and the other in 

 the Miocene. This is the grouping of the strata followed by the late 

 Sir Charles Lyell ; and no one who has studied the faunas of the 

 Hempstead beds, and of their equivalents the Fontainebleau Sand- 

 stone of the Paris basin, and the Eupelian of Belgium, can for one 

 moment doubt that this classification is well founded. The fauna 

 of the Fontainebleau Sandstone and of the Eupelian being unques- 

 tionably more closely related to the Miocene than to the Eocene, it 

 is quite impossible to accept the grouping adopted by the Geological 

 Survey, and followed in most Englis'h text-books of geology, and to 

 extend the Eocene or ^ummulitic series upwards so as to embrace 

 beds containing such faunas as those of the Brockenhurst and Hemp- 

 stead series. 



On the other hand the inconvenience of breaking up so natural a 

 group of strata as that which the fluvio-marine beds of the Hamp- 

 shire basin manifestly constitute is apparent to every one ; and it is 

 doubtless this conviction which has operated in preventing the general 

 acceptance of the Lyellian classification. It has been felt, and rightly 

 too, that no such break in continuity exists between the Hempstead 

 and Bembridge strata as would warrant their being placed in distinct 

 divisions of the geological series. 



Fortunately a method of classification is open to us which, while 

 it does not break up this natural group of the Fluvio-marine of the 

 Hampshire basin, yet enables us to refer its members to divisions of 

 the geological series which have been based on the careful and exact 

 study of the faunas of the Tertiary strata all over Europe. This 

 classification completely satisfies the apparently opposing require- 

 ments of the physical geologist and the palaeontologist. 



In the year 1854 Prof. Beyrich, in describing the nature and 

 affinities of the fauna which was yielded by the Tertiary beds of 

 Northern Germany, pointed out that the same difficulty is found in 

 defining whether they should be regarded as Eocene or Miocene as 

 is the case with the English strata which we are now considering. 

 He further showed how recent discoveries had added greatly to the 

 importance which must be attached to the beds on this horizon, 

 beds which he has demonstrated to be represented by deposits of 

 great thickness, not only in Hampshire but in the Paris basin, Bel- 

 gium, the Mayence basin, and j^orthern Germany ; and he suggested 

 that these strata form a division of such consequence, and contaiuiug 

 a fauna so distinct, that they deserve to be erected into a new 

 grand division of the Tertiary series. For this division of the 

 geological series Prof. Beyrich proposed the name of " Oligocene," 

 a term formed on the same principle as was adopted by Lyell in 

 devising names for the other divisions of the Tertiary strata. 



This division of the Tertiary series, to which Beyrich applied 

 the name of Oligocene, has now come to be very generally recog- 



