We continued through the unchanging soil.
One of the many mine shafts had another minecart with a strange sack hidden inside it. We took it and the cart that held it, to cart our things (hopefully) back towards the surface. Venrick was the one to identify it as a bag of holding, as well as an unusual rock and a shortbow. The bow was etched with fearsome runes, and the rock repairs and fortifies whatever it is attached to.
We took ten minutes to reorganize and move on.
The bottom of the shaft mining area was hastily barricaded. We cleared the tracks and used the uphill minecart as a battering ram, sending it careening downhill. It destroyed the barricade with a resounding crash.