Footage:

https://youtu.be/LSdAvWSSPho

Info:

• There is a huge "station" in about 30-40 blocks forward in the direction I was mining the cobblestones.
• The station has 4x 3x3 "tube" to the surface at it's corners where the light comes in.

Situation:

• Blocks around the tube's end (where direct sunlight reach the bottom) will recieve sunlight, no matter how much they are obscured.