Valleys: (Filling up of) of Removing all Obstructions to the Gospel
Source: TTT
Isaiah 40:4
Every valley shall be lifted up, and every mountain and hill made low; the uneven ground will become smooth, and the rugged land a plain.
Luke 3:5
Every valley shall be filled in, and every mountain and hill made low. The crooked ways shall be made straight, and the rough ways smooth.