Green’s Dictionary of Slang

clarge n.

[? dial clart, thick stucky mud or filth]

thick, viscous mud.

[UK]J. Dunlop Agatha in Sthn Argus (Port Elliot, SA) 14 Apr. 4/1: [T]he houseless and wretched [...] crawl through the ‘clarge’ (mud — excuse the slang; it is expressive) as though, with eels, it were their native element.