sacrifice
垗 centers on a place of sacrifice, specifically an earthen altar or mound used for ritual offerings.
垗 combines 土 (earth) with 兆, which likely contributes the sound. The character refers to an earthen altar for sacrifices.
The left side is earth 土, and the right side 兆 looks like a sign or omen. Picture an earthen mound marked with a sign where sacrifices are offered.
For チョウ, imagine a long-serving chief named Chou standing at the earthen altar, overseeing the sacrifice: Chou -> チョウ.