W. Whitaker — Geologij of Coasts of England and Wales. 65 



beyond this the London Clay appears for the first time in the cliffs, 

 from beneath the Crag ; and the Felixstowe cliffs also consist of Crag 

 over London Clay. On crossing Orwell Haven to Harwich we have 

 more than a mile of cliff of London Clay alone (Dovercourt). Thence 

 marshes and tidal creeks set in, and alluvial clay comes down to the 

 shore and also forms the foreshore to the Naze, which consists of 

 London Clay, partly capped by Crag and Drift. 



From Walton to Frinton we have more than 2 miles of London Clay 

 cliff, and then, after an alluvial gap of a mile, some 4 miles of London 

 Clay capped by gravel. 



Westward and southward from this we have no cliff for many 

 a mile. The marshes reach down to the beach as far as the estuary 

 of the Colne. Mersea, between the Colne and the Blackwater, is 

 a cliffless island. Between tlie Blackwater and the Crouch (more 

 than 8 miles) we have generally a broad tract of marshes, the London 

 Clay reaching to the coast only at one spot, on the north, the site of 

 a Roman station (Ithanchester), and then not forming a cliff. From 

 the Crouch to Shoeburyness there is again a tract of marshland, which 

 is of considerable extent and mostly in the form of islands, owing 

 to the River Roach and its attached creeks cutting through from side 

 to side. 



Westward from Shoeburyness, up the estuary of the Thames, there 

 is at first a low-lying mass of gravel and loam, forming only a very 

 small cliff in parts, with London Clay at the base sometimes. At 

 Southend the ground rises and there are cliffs of London Clay to Leigh, 

 ■where the marshes of the Thames begin. 



Crossing the Thames there are again marshes, gravel and London 

 Clay reaching the shore only north of Allhallows, and the latter again 

 at the eastern end of the Isle of Grain. 



Crossing the Medway to Sheppey, at and near Sheerness the marshes 

 reach to the shore ; but the London Clay soon rises up and forms cliffs 

 of fair height along the greater part of the island, the highest parts 

 having caps of Bagshot Sand and gravel. At the eastern end the 

 marsh is separated from the sea b)' a beach of shells. 



On the other side of the Swale, from Whitstable to beyond Heme 

 Bay, we have some miles of London Clay cliffs, varied here and there 

 by their coverings of gravel or loam. Then the Lower London 

 Tertiaries (here consisting mostly of sand, but with some clayey beds 

 in the lower part) rise up and at length reach the cliff-top three 

 quarters of a mile westward of Reculvers. 



The rise of the Chalk from beneath the Tertiary beds is hidden 

 by the 2h mile wide marshes of the Wantsum ; but passing these we 

 come to the Isle of Thanet, which is bounded almost wholly by chalk 

 cliffs, there being a very few small gaps of Alluvium or Valley Drift ; 

 the thin cappings of loam in places are of no moment in this enquiry. 

 In the lower ground westward of Ramsgate the Thanet Beds (sand 

 and marly beds) come on over the Chalk somewhat suddenly and form 

 a cliff for a short way. 



Then southward, across the valley of the Stour, is a broad tract of 

 marshland, bordered, from the river nearly to Deal, by a strip of Blown 

 Sand (at one part over half a mile broad) with an outer margin of 



