206 CHRONOLOGICAL RELATIONS 



CHAPTER Xn. 



ANTIQUITY OF MAX RELATIVELY TO THE GLACIAL PERIOD AND 

 TO THE EXISTING FAUNA AND FLORA. 



CHRONOLOGICAL RELATION OF THE GLACIAL PERIOD, AND THE EARLIEST 



KNOWN SIGNS OF MAN's APPEARANCE IN EUROPE SERIES OF TERTIARY 



DEPOSITS IN NORFOLK AND SUFFOLK IMMEDIATELY ANTECEDENT TO THE 



GLACIAL PERIOD GRADUAL REFRIGERATION OF CLIMATE PROVED BY THE 



MARINE SHELLS OF SUCCESSIVE GROUPS MARINE NEWER PLIOCENE 



SHELLS OF NORTHERN CHARACTER, NEAR WOODBRIDGE SECTION OF THE 



NORFOLK CLIFFS NORWICH CRAG FOREST BED AND FLUVIO-M ARINE 



STRATA FOSSIL PLANTS AND MAMMALIA OF THE SAME — OVERLYING 



BOULDER CLAY AND CONTORTED DRIFT NEWER FRESH-WATER FORMATION 



OF MUNDESLEY COMPARED TO THAT OF HOXNE GREAT OSCILLATIONS OF 



LEVEL IMPLIED BY THE SERIES OF STRATA IN THE NORFOLK CLIFFS 



EARLIEST KNOWN DATE OF MAN LONG SUBSEQUENT TO THE EXISTING 

 FAUNA AND FLORA. 



FREQITENT allusions have been made in the preceding 

 pages to a period called the glacial, to which no reference 

 is made in the Chi'onoloo-ical Table of Formations ffiven at 

 p. 7. It comprises a long scries of ages, chiefly of post- 

 tertiary date, during which the power of cold, Avhether 

 exerted by glaciers on the land, or by floating ice on the 

 sea, was greater in the northern hemisphere, and extended 

 to more southern latitudes, than now. 



It often happens that when in any given region we have 

 pushed back our geological investigations as far as we can, in 

 search of evidence of the first appearance of man in Europe, 

 we are stopped by arriving at what is called the "boulder 

 clay" or " northern drift." This formation is usually quite 

 destitute of organic remains, so that the thread of our in- 

 quiry into the history of the animate creation, as well as of 

 man, is abruptly cut short. The interruption, however, is by 



