HEAD ON HILL AKD COLWELL BAT IN THE ISLE OF WIGHT. 



97 



Lower Headon of Warden Cliff. — The lowest beds seen are below 

 the Totland Bay Hotel at Weston Chine. We therefore start from 

 here in making a measure of the Lower Headon series, meeting higher 

 beds as we go north towards Warden Point. The details of this 

 measurement are given in the vertical section, fig. 2 (p. 98) ; we need 

 here allude to only a few of the beds. The lowest bed seen in 

 Totland Bay is a few yards south of the Coast-guard boathouse ; 

 here are visible, in ascending order, whity-brown sands, 1| foot, a 

 hard purple sandy ironstone, 6 inches, greenish clay, 4 feet. 



In our vertical section, fig. 2, we have drawn an interruption in these 

 clays, because we are not absolutely sure that they are identical with 

 the similar clay in the road-cutting at the pier-head on the other 

 side of the boathouse; there is little doubt of it, however. At the 

 pier-head are seen 3 feet of clay in the road-cutting (after our 

 section was drawn, on a later visit, a drain-opening showed feet) ; 

 and from this point the section is continuous without interruption. 

 There is therefore only a possibility of error of a few feet. 



Five thin Limnsea-limestones will be noticed. The two lowest 

 contain Chara-seeds at the pier- head ; on following them to their 

 outcrop along the shore it is found that the fourth of them also 

 has Chara-seeds at that point ; the fifth, 1 foot 3 inches thick, is 

 50 feet below the top of the How-Ledge limestone, or top of the 

 Lower Headon. 



From the top of the cliffs these limestones may be seen at low 

 water, forming five submarine ledges parallel to the great ledge at 

 Warden Point; they strike N. 36° W. 



As there is great uniformity in these freshwater beds, and their 

 fossils mostly occur in the Upper Headon also, we pass over many beds 

 to notice the sand-rock bed, which is a conspicuous feature in Warden 

 Cliff. This sandstone, somewhat calcareous at places and friable at 

 others, forms Warden Ledge, and runs out at the top of the cliff 

 close below the flagstaff of the coast-guard station. 



About 11 feet above that comes the Unio Solandri bed* with 

 Melania turritissima, a bed of which we have already noted a portion 

 in the cliff at Widdick Chine ; the M. turritissima occurs through 

 a greater thickness of the 11^ feet of clays than does the Unio. 

 Next comes the How-Ledge limestone, 5 feet, in two beds containing 

 Limncea fusiformis, with a carbonaceous or lignitic band at the base. 

 The shells are more crowded at the base ; and the lower surface of 

 the blocks fallen from the cliff is a sight pleasing to the collector 

 of fossils. The dip of this bed in Warden Cliff, calculated from its 

 horizontal extension on the 25-inch map, between its position at How 

 Ledge at sea-level and a point of known elevation near the flag- 

 staff, is a slope of about 1 in 45. This How-Ledge bed crops out at 

 the top of the cliff, a little north of the coast-guard flagstaff ; it is 



* The Unio-bed with Melania turritissima occupies an analogous position at 

 Hordwell Cliff, being at about the same distance below the Lynmsea-limestone 

 (which is a diminutive representative of the How-Ledge bed), where it has pre- 

 cisely the same lithological characters with the same abundance of black seeds 

 (Carpolithes) as at Colwell Bay and Warden Cliff ; it crops out again with the 

 same fossils on the shore immediately south of Milford. 



