1

North side Wealden Denudation

Chalk at North side    600 ft                    600

Upper Greensand      60-80 ft                 70

Gault                      80 to 110 ft            90

Lower Greensand      350 ft                     350                        22 miles                                                                                     --------

                                                          1115

South side  March 1857 (In about year will view more)

Chalk on S side        700 to 800                                  750

Upper Greensand      50 feet (outside)                         40

Gault    Greensand at 80 to 100                                    90

Lower Greensand probably about 200 ft                        200

                                                                             -------

                                                                             1080

1 y [year] 1100 feet thick, & the denudation of Wealden seen not included.— It is 22 miles

From edge to edge of Wealden is & much further

East [edge to edge] & then is strips of miles or two on each side to Chalk, but we will say only 22 miles.    

Miles from edge to edge of Wealden. 

Land                                                   1760 yards to north

-  22   As we suppose 1 inch of cliff — 500 ft in cutting cliff of 1100 feet will take 220 years

3520            

3520.           

Rivers [illeg] when dry land 38720

                                                               36

232320

Land   116160.

1393926 inches

       220 thus why it ought to be 210

27878400

2787840.
306, 862, 400 Million years since Cretaceous deposit

Darwin made and revised estimates in chapter IX of Origin, most famously in his discussion of the denudation of the Weald in Origin, pp. 285-286.