258 EARTH FEATURES AND THEIR MEANING 



this lower submerged opening and has been robbed on the way of 

 all but its blue rays which gives to the famous grotto its special 

 charm (Fig. 289). 



It is known that the former, and now submerged, sea cave was 



in use by Roman patricians as a 

 cool retreat from the oppressive 

 hot wind known as the sirocco, 

 and that an artificial entrance or 

 window was cut where is now the 

 only accessible entrance to the 

 grotto. In the ancient writings, 

 no mention is made, however, of 

 FIG. 289. Cross section of the Blue the remarkable blue illumination 

 Grotto on the island of Capri, show- f or which it is now famous, and 

 l^rt^e^nntrt the conditions at the time, as we 

 grotto, and the higher artificial win- may see, were not such as to make 



dow now widened by wave action this possible. Later subsidence 



of the coast has brought the 



ancient window to the sea level, where it has been considerably 

 enlarged by the waves. The earlier grotto, abandoned as its 

 entrance was closed, was rediscovered in 1826 by the painter and 

 poet, August Kopisch. 



A grotto with green illumination (the Grotto Verde) is situated 

 upon the opposite side of the island, and a blue grotto, having its 

 origin in similar conditions to those of the famous Blue Grotto, 

 is found upon the island of Busi off the Dalmatian coast. 



Character profiles. In the landscape of a coast which has been 

 slowly uplifted the characteristic line is the profile of the cuesta, 

 with short perpendicular element joined to a gently sloping and 

 longer section and continued in the horizontal portion correspond- 

 ing to the lowland (Fig. 290). Rapidly uplifted coasts offer in 

 contrast the lines characteristic of wave erosion and deposition, 

 but at higher levels and in repeated sections. Most prominent 

 of all is the staircase constructed of coast terraces, with either 

 vertical or sloping risers and with outwardly inclining and gently 

 graded treads. Near the steep riser in the staircase may some- 

 times be seen the sugar-loaf outline of the stack cut in softer ma- 

 terial, or the obelisk-like pillar undercut at its base, which is carved 

 in firmer rock masses. With excessively rapid uplift, the double- 



