Helderbergian

Helderbergian

[‚hel·dər′bərg·ē·ən]
(geology)
A North American stage of geologic time, in the lower Lower Devonian.
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References in periodicals archive ?
The lower two units of dark shale, chert, and cherty limestone did not yield diagnostic fossils, but were provisionally placed in the earliest Devonian (Helderbergian) by Wilson and Majewske (1960).