archaeology n.

before vowels archae-, word-forming element in scientific compounds meaning "ancient, olden, primitive, primeval, from the beginning," from Latinized form of Greek arkhaios "ancient, primeval," from arkhē "beginning," verbal noun of arkhein "to be the first," hence "to begin" (see archon).

word-forming element indicating "branch of knowledge, science," now the usual form of -logy. Originally used c. 1800 in nonce formations (commonsensology, etc.), it gained legitimacy by influence of the proper formation in geology, mythology, etc., where the -o- is a stem vowel in the previous element.

The second element is prop[erly] -logy (-logue, etc.), the -o- belonging to the preceding element; but the accent makes the apparent element in E[nglish] to be -ology, which is hence often used as an independent word. [Century Dictionary]