100 



win's theory is doubtless true in some and Murray's apparently 

 more lucidly explains others. 



Deep borings made on the atoll of Funafuti under the direc- 

 tions of the Royal Society revealed coral rock at the foundation 

 of an atoll, at a depth of 1,000 feet below the level at which these 

 animals can live, which clearly indicates a fall in the ocean bed, 

 whilst on the other hand many borings are found to be less than 

 1 20 feet. The matter of formation is still under investigation and 

 atolls have been referred to as " garlands laid by the hand of 

 Nature on the tomb of departed islands" (Duke of Argyll). 



The " white cliffs of Albion " is a phrase which has endeared 

 itself to the heart of every Englishman and the thrill is most im- 

 pressive when homeward bound after a season of absence. 



The peculiar jointing of chalk and limestone call for a little 

 attention since the peculiarities of jointing and bedding are quite 

 unique to the series and lend a landscape picture pertaining to 

 chalk alone. Originally in common with sedimentary rocks the 

 strata were horizontal and in places the horizontal layers are well 

 preserved. Earth movements , which are almost continual owing 

 to slowly radiating heat, produce wrinkling by which folds are 

 prepared in a manner analagous to the shrinking of an apple and 

 the consequent waving of the skin. The lateral pressure, exerted 

 by continual shrinkage, applied to the sedimentary nature of the 

 laminae in chalk, causes secondary cracks and fissures to assume 

 vertical directions and cracks are thus produced which segment 

 the chalk into almost cubical blocks. This is markedly seen in the 

 stacks at Swanage and in Old Harry. The cubical nature of 

 segmenting is inherent in the chalk and is partly the cause of the 

 vertical faces of chalk cliffs. The cliffs of limestone are similar 

 in appearance to the chalk, but the cubes are larger and bolder 

 than those of chalk, as for example the cliffs at Tilly Whim. 



Fissures of a larger nature are frequently due to insecure 

 foundations or the slipping on a lower bed upon which the chalk 

 rests. Excellent examples are to be found of this type of fissure 

 near Sandsfoot Castle and Bow and Arrow Castle on the Isle of 

 Portland. 



Chalk cliffs present, as a rule, a vertical front to the sea. 

 This follows upon the nature of its jointing and bedding. Por- 

 tions which become detached through weathering leave a front 

 parallel to,, the original front, and thus perpendicularity is ensured 

 as the cliffs weather and fall away. 



Chalk stacks, too, are a special feature of chalk. Locally 

 two familiar landmarks of our bay and coastline are the Needles 

 and Old Harry. These stacks, which have been severed from the 

 mainland by the continual bombardment of the sea, are left 

 ultimately as isolated pinnacles when the less resistant material 

 has been carried away. They have thus been chiselled by nature 

 out of the solid mass. 



Contrast for example the scenic effects of the limestone cliffs 

 of Tilly Whim, the chalk of Ballard Down and the sand of 



