hypabyssally

hyp·a·bys·sal

 (hĭp′ə-bĭs′əl, hī′pə-)
adj. Geology
Solidifying chiefly as a minor intrusion, especially as a dike or sill, before reaching the earth's surface. Used of rocks.

hyp′a·bys′sal·ly adv.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

hypabyssally

(ˌhɪpəˈbɪsəlɪ)
adv
(Geological Science) in a hypabyssal manner
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014