456 Wood and ffarmer — Geology of Norfolk and Suffolk, 



some parts is below that of the Crag, and nearly 100 feet below the posi- 

 tion which it occupies when resting on the older Glacial beds in undis- 

 turbed sequence of deposit, the Chalk upon which the Upper Glacial 

 thus rests direct, being generally in a glaciated or disturbed condition. 



That over the central part of Norfolk, where the Upper Glacial 

 thus goes down in solid mass to the Chalk, it is overspread by exten- 

 sive beds of Post-glacial gravel,^ which not only cap the plateaux, 

 but spread over the sides of the valleys, sometimes forming a con- 

 tinuous wrapping sheet down to their bottoms, and presenting a 

 general absence of terrace structure. These features the authors 

 consider as repugnant to any theory accounting for the excavation of 

 the valleys by river-action. Similar old Post-glacial gravels are 

 also present, but less extensively, in eastern Norfolk, where they 

 rest on the denuded surfaces of the Upper and Middle Glacial forma- 

 tions ; large sheets of them capping the former at Poringland, and 

 the latter at Household Heath. 



That, in addition to these older gravels, sheets of a newer gravel, 

 more or less concealed by the alluvium, occupy the bottoms of most 

 of the river- valleys. This newer gravel they consider may be the 

 deposits of the rivers during the Post-Glacial period, and after the 

 valleys had been formed by tidal action. 



The sequence of the beds, omitting the Post-Glacial, may be 

 summed up as follows, the beds being taken in descending order : — 



1. The Upper Glacial, or true Boulder-clay, of the East of England \ p. + „f xi,. 



2. The Middle Glacial sands and gravels ^ (Glacial 



3. The Contorted Drift, beginning as a thin bed in the North-east of i o • 



Suffolk, and thickening out towards the Norfolk coast / 



4. The Pebbly sands and Pebble beds. 



5. The Chillesford Clay ^ 



6 Sands containing the Chillesford shell-bed^ or Crag of Chillesford, | m_„- tTtatao,. 

 Sudbourn Church Walks, Easton Cliff, and Aldeby, and Upper \^^^ g^PPf^ 

 bed of Bramerton j ° 



7. The Bed and Fluvio -marine Crag J 



The Weybourn sand (A), the Cromer Till (B), and the indenting sand (C), (which 

 with the contorted drift make up the Lower Glacial formation), come in below the bed 

 No. 3, which spreads over them and over No. 4 ; but as they are absent where 

 No. 4 is present they, as before explained, may either represent No. 4, or No. 4 may 

 be only the uppermost member of the true Crag series. 



In South-east Suffolk No. 2 rests on 5, 6, or 7, but most frequently on No. 7 ; 

 Nos. 5 and 6 having been much denuded prior to the deposit of No. 2. 



:k,:ei^v^i:h]^v^s. 



I. — A Journey in Brazil. By Professor and Mrs. Louis Agassiz. 

 Boston : Ticknor and Fields. London : Trtibner and Co., 60 

 Paternoster Eow. 1868. 8vo. pp. 540, with 20 woodcut en- 

 gravings. 



" nnO Mr. Nathaniel Thayer, the friend who made it possible to 

 I give this journey the character of a scientific expedition, the 



^ In the small map of the Glacial beds of the east of England, printed by one of 

 the authors for private circulation in 1865, the centre of Norfolk, where these Post- 

 glacial sands and gravels so extensively occur, was represented as principally occupied 

 by the sands and gravels of the Middle Glacial series. This error, which the prose- 

 cution of their work has detected, the authors desire to call to notice. 



