From Longman Dictionary of Contemporary Englishshaleshale /ʃeɪl/ noun [uncountable] HEGa smooth soft rock which breaks easily into thin flat pieces
Examples from the Corpus
shale• The track ran parallel to the South Coast Expressway, through land that was flat, a wasteground of weeds and shale.• Its sides were neither high nor sheer, just slopes of black shale rising no more than fifty feet.• This indicates the sandstones can be over 30 m thick and are separated by well-defined shale beds.• The buried forests became seams of coal and the strata of mud and sand hardened into shale and sandstone.• Bring on those sheets of jagged shale, for at least they are firm!• It was a telltale sign that water was seeping through the canyon walls, softening the mica shale and conglomerate abutment.• Quite simply because men must shale Parenting if women are to lead full lives.• It would only have needed one postponement at the school's shale pitch to have wrecked Errol's big opportunity!Origin shale Old English scealu “shell, scale” 