THE ISLE OF PORTLAND. 393 



The cliff in Ringstead Bay is rich in the usual 

 fossils of the Kimmeridge beds ; and Osmington 

 Cliff, west of Ringstead, abounds in Trigoniae and 

 other shells of the Oxford clay, many of which are 

 in a beautiful state of perfection. Crystals of 

 sulphate of lime, or selenites, are common in 

 the clays. 



The Isle of Portland. — Though beyond the 

 limits originally prescribed to these excursions, 

 the Isle of Portland, which we have seen looming 

 in the western horizon during the greater part of 

 our progress from the Isle of Wight, is so inti- 

 mately related in its physical structure with the 

 country over which our observations have ex- 

 tended, that some notice of that interesting spot 

 is necessary, to afford a comprehensive view of the 

 geological phenomena, which this volume is de- 

 signed to illustrate. 



The Isle of Portland is a bold headland on the 

 south of Weymouth, about four and a-half miles 

 in length, and two in breadth, united to the main- 

 land by a bar of shingle termed the Chesil Bank. 

 It presents a precipitous escarpment on the north 

 about 300 feet in height, and declining towards 

 the south, appears, when viewed from the east 

 or west, like an insulated inclined plane rising 

 abruptly from the sea. The substratum or foun- 



