76 
CRUISE OF H.M.S. CHALLENGER. 
at the bottom of the Atlantic is obtained from Ant- 
arctic sources. Nine important stations had been 
examined on our way, showing an average depth of 
2500 fathoms. 
Late on the evening of the 28th we observed the 
light on Gibbs Hill, Hamilton, sparkling brightly 
ahead. Hove-to for the night, and for the next two 
days continued sounding and dredging round the reefs. 
Swung ship both for magnetic and azimuth correc- 
tion, after which stood in for the Narrows, got the 
pilot on board, and a few hours later we were along- 
side the jetty of the Naval Yard, where we found 
H. M. ships Terror , Sirius , Minstrel , Fly, and Brito- 
mart. Here we remained for ten days refitting 
and completing stores, and during this interval 
many scientific excursions were made about the 
islands. To the geologist, particularly, the exa- 
mination and phenomena of the sand glacier were 
exceedingly interesting. It appears that the fine 
coral debris which surrounds the shore is caught at 
certain exposed parts of the coast by the prevailing 
winds, and so blown into heaps more than 30 feet 
in height. We were informed that on some parts of 
the southern shore, where deep valleys once existed, 
level plains are now to be seen. And this is still 
going on, overwhelming gardens, houses, and planta- 
tions in its way, and but few attempts appear to be 
made to stay its progress. 
In some places where these great heaps of sand 
