Walker's focus was not on gathering earth mana. It was a pure focus on the fact that the carving surrounding him were better than many things he could create. His mind had to focus on what kind of skills would have been used. Was it a sculpting skill better than a high sculpting skill? Or was it a skill of a better class altogether?
These questions were what Walker was stuck on and needed to figure out. Especially because he was unsure whether or not he would be able to use them. It was definitely a fact that the earth dominator dragons or the ancient earth dragons had not used mastery skills to make this. This brought him to the next theory, a mix of skills used in combination to create them.
drop those golden tickets!