(See quot. 1859.) Also in combinations, as floetz-trap.
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1811 J. PinkertonPetralogy I. 99 It belongs to the floetz-trap rocks.
1859 D. PageHandbk. Geol. Terms 169Flötz..a term applied by Werner to the Secondary strata, because they were flötz or flat-lying, compared with the primary and transition rocks.