These landscape 'features' are certainly spoil tips associated with the construction of the Settle-Carlisle Railway in the area adjacent to what is now the south portal of Blea Moor Tunnel. However, it is not clear if the spoil came from
- the cutting immediately to the south of the portal,
- a 'cut-and-cover' cutting [see note 1] immediately beyond (to the north of) the portal,
- a conventially mined section of the tunnel somewhere beyond (to the north of) the portal, or
- some combination of these sources.
Note 1: The suggestion that the southern end of the tunnel might have been constructed using the 'cut-and-cover' technique comes from the following (generally well-regarded) contemporary account:
We can now see through the “spectacles” of the powerful little engine which is drawing us, that we are approaching the mouth of what may perhaps be more strictly called the " covered way" that leads to the famous Blea Moor Tunnel. It was intended to make the entrance some distance farther north; but eventually it was thought safer (in order to avoid any slipping of earth down the mountain or down the sides of the cutting, which would have been nearly 100 feet deep) to cover in the cutting, and, in effect, to commence the tunnel 400 yards farther south.
Source: F.S. Williams: "The Midland railway: its rise and progress. A narrative of modern enterprise" (Published by Strahan & Co London in 1876).