The dwarves in my world are humans who starting digging caves in the Maumturks and Twelve Bens in Ireland during the Iron Age, and eventually connected the caves via tunnels rather than trudge across the bogs that surround the hills. The rough timeline I have is that the caves start during the Iron Age, and by the 1500s the connecting tunnels are a well-established continuous network. Ignoring the fact that Iron Age humans would have very little reason to do this in the first place, I have the following problems:
- The Maumturks and Twelve Bens are a mix of quartzite and granite, both of which are very hard rocks.
- The length of the required tunnel network. For the sake of reference, here's a map that I've centred on the Maumturks (running from Leenaun down to Maum Cross, west of what's now the R336). The main network along the Maumturks would be approximately 20km long - and that doesn't include branch tunnels, or multiple levels going in the same direction.
So, could humans do this with hand tools, and if so, how long would it take?