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a fairly definite epoch. And to us in this part of England it is a 

 familiar formation, devoid of the dimness and strangeness con- 

 nected with more distant periods such as are illustrated by the 

 rocks in Scotland or the extreme west of Englan 1. Let us com- 

 mence then with the Chalk age. 



It is I s appose hardly necessary to point out to you that chalk 

 is a marine deposit, full of sponges, fish remain?, and shells of 

 molluscs, from which its history is eadly extracted. What and 

 where was Great Britain in those days ? Since the chalk is a deep 

 sea formation, if we trace out the chalk deposits in England we can 

 tell at least what parts were covered with sea in those far-oif times. 

 Note then how the chalk occura in our island. We have our own 

 local range of the North Downs reaching from our clifts as far to 

 the west as Salisbury Plain. Nearly parallel runs the range of 

 the South Downs from Beachy Head to the same place. A short 

 spur extends south into Dorsetshire, and disconnected outliers are 

 found in Devonshire. A great escarpment runs from Salisbury 

 Plain, north-east to the Wash, re appears in Lincolnshire, and 

 again in Yorkshire, terminatng in Flamboro' Head. Then un- 

 doubtedly all those districts were under the sea in Chalk times. 

 But we cannot limit the submergence to those parts ; if what are 

 now lulls formed the bed of the sea so did the lower lying districts 

 between these ranges occupy a similar position, and furbher, they 

 must have been covered with the s^me deposit of chalk, which has 

 since been removed by various natural agencies. 



But now we also find chalk in Ireland in the County of Antrim, 

 and again on the West of Scotland in the island of Mull, and in 

 the district of Morvern in Argyleshire. The sea must thus have 

 extended at least to those parts, how much farther it is not easy to 



Let us try to realize the physical condition in which our islands 

 then lay. There was certainly no island corresponding to what we 

 call Great Britain. Whatever of land there may have been before 

 then, geologists are pretty certain of the foil 'wiag facts: — the 

 whole of what is now the eastern and central parts of England 

 gradually sank, the slope being as at present towards the east, and 

 the eastern waters (where the North Sea is now) slowly encroached 

 upon it. First the Lower Greensand was laid doAvn, then the 

 Gault, and as the depression went on, the Upper Greensand, not 

 evenly everywhere, in some places not at all, for the depression 

 was not necessarily uniform, and the high grounds were of course 

 the last to be submerged. Still the sinking continued until this 

 old sea washed the feet of the Welsh Mountains, reached into 

 Devonshire, and stretched north-west across to Ireland, and along 

 the west of Scotland. Then the highest parts of Wales became 



