1. marl - Noun
2. marl - Verb
To cover, as part of a rope, with marline, marking a pecular hitch at each turn to prevent unwinding.
A mixed earthy substance, consisting of carbonate of lime, clay, and sand, in very varivble proportions, and accordingly designated as calcareous, clayey, or sandy. See Greensand.
To overspread or manure with marl; as, to marl a field.
Source: Webster's dictionarySo this is hell. I'd never have believed it. You remember all we were told about the torture-chambers, the fire and brimstone, the "burning marl." Old wives' tales! There's no need for red-hot pokers. Hell is-other people! Jean-Paul Sartre
A layer of phosphatic nodules ( coprolites ) under the marl were mined in the 19th century for fertiliser. Source: Internet
A sandy stratum, glauconitic marl (tortia), is in between the chalk marl and gault clay. Source: Internet
Also visible is the segmented tunnel lining Surveying undertaken in the 20 years before construction confirmed earlier speculations that a tunnel could be bored through a chalk marl stratum. Source: Internet
Flyvbjerg et al. p. 3 Construction Working from both the English side and the French side of the Channel, eleven tunnel boring machines or TBMs cut through chalk marl to construct two rail tunnels and a service tunnel. Source: Internet
For most of its length the tunnel bores through a chalk marl stratum (layer) Successful tunnelling required a sound understanding of the topography and geology and the selection of the best rock strata through which to dig. Source: Internet