Rosehip isn't digging like an excavator, more like a mole, look! She hit a rock!
And uhh...Katyusha, how did you know Brazil?

At least Rosehip is digging sideways instead of down. If you dig a hole too deep without reinforcing the sides, it can spontaneously collapse. Now and then you will hear on the news of people just "digging a hole" and something bad happens, or trench collapses at construction sites. Just like with water, the pressure in the ground material increases with depth, and if that pressure exceeds the forces holding the material together it will collapse to fill the void.