10 



For the sake of such of my heai'ers as are not geologists, I 

 may observe here that this formation is one of the Tertiary beds, 

 the newest, with the exception of the Post Tertiary and those 

 Alluvial beds in course of formation at the present day. 



The Tertiary beds are subdivided into Eocene, Meiocene, 

 and Pleiocene — these names indicating their respective characters 

 as derived from the proportion of recent shells found in them 

 {or species still living) compared with the number of those which 

 Are now extinct. 



In the Eocene, or oldest of these beds, the per centage of 

 recent shells is extremely small ; in the Meiocene, the recent 

 species are rather more numerous, but are still in a minority ; 

 in the Pleiocene they are so much increased as to constitute 

 the majority. 



The Red Crag of Suffolk is one of the older beds of the 

 Pleiocene formation. " It consists chiefly of quartzose sand, with 

 ■" an occasional intermixture of shells, for the most part rolled, 

 " and sometimes comminuted, and is distinguished by its deep 

 " ferruginous or ochreous colour from an older and lower bed of 

 *' Crag, commonly called the White or Coraline Crag." 



It was in this Red Crag that Professor Henslow first noticed 

 the occurrence of certain nodules or concretions, abundantly 

 interspersed among the comminuted shells which form the upper 

 part of the cliff. They were extremely hard, and presented 

 external indications of an animal origin. He was much puzzled 

 to account for them ; and on a second visit to Felixstow, during 

 the summer of 1843, he gave them a further examination. The 

 December following, at a meeting of the Geological Society, he 

 exhibited a series of specimens of those nodules, pointing out 

 their several peculiarities, and the various forms under which 

 they appear.* 



* Proceed. Geological Society, 1843, p. 281. 



