How many letters does the top answer for “of or pertaining to geogony, or to the formation of the earth.” have?

The most common answer is geogonic (8 letters).

Crossword clue: of or pertaining to geogony, or to the formation of the earth.

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

geogonic 8 letters web-def

Of or pertaining to geogony, or to the formation of the earth.

geogonical 10 letters web-def

Of or pertaining to geogony, or to the formation of the earth.

of or pertaining to the earth. 50% similar → tellural