Deletion of Social Hall (Alcatraz)

Comment: The topic is notable.  For example, https://books.google.co.uk/books?id=Z2dOAQAAIAAJ this source discusses the geology of this feature in detail.  See also ; ; ; ; 
Stance: keep
Cited policy: Wikipedia:Deletion policy (WP:ATD||WP:BEFORE||WP:NOTCLEANUP||WP:NOTPAPER||WP:PRESERVE)