I could not understand why I was unable to put a sand pit on a deep sand resource. after 15 minutes of attempting to flatten the ground I learned through google that a special building was required.
The map I am on only has deep resources close to my starting location which feels like punishing me early and making things too easy late in the game. I would suggest that a regular sand pit (or other resource building) be able to gather a certain amount of the deep resource which you can then replace once you hit tier 4, Or simply have deep recourses become discoverable at tier 4, or maybe have the map generate “deep” resources farther away from your starting point but also available via regular buildings if you are brave enough to go out to them early.
Now returning to this game after about a year I was very confused and frustrated over the “deep” recourses to the point that I felt it was poor design.