The term "magmatype" and the terms olivine basalt and tholeiitic basalt have been found inapplicable to the two prevalent basalt types of the British Tertiary province. In their place are suggested Hebridean type (to replace Plateau magma-type and olivine-basalt magma-type) and Causeway type (to replace nonporphyritic magma-type and tholeiitic magma-type). The Hebridean type is characterized by predominance of plagioclase (labradorite) over pyroxene, whereas the Causeway type is characterized by a lesser abundance of plagioclase (andesine) relative to pyroxene. The two types can be subdivided into two subtypes each.

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