Final answer:
Hell Gill Force is a waterfall formed by the erosion of softer sandstone by river water, which has created a steep-sided gorge below it. As the water eroded the land, the gorge's shape reflects the waterfall's gradual retreat backwards over time, showcasing the profound impact of water on landscape formation.
Step-by-step explanation:
Hell Gill Force is an erosional geological feature known as a waterfall, which is typically formed in an area where there is an abrupt change in rock hardness within the river channel. This waterfall, in particular, is situated near the source of the river Eden, and it has formed at the transition point from hard limestone to softer sandstone. As the river water flowed over this boundary, it gradually eroded the softer sandstone faster than the limestone, creating a step-like feature, which we recognize as the waterfall.
Below Hell Gill Force, the continued erosion by the waterfall—which often happens as water plunges down, eroding the base and causing the waterfall to 'retreat' backward—has resulted in a steep-sided gorge. This gorge is a characteristic aftermath of such retreating waterfalls, telling a story of how the landscape was shaped over time. This natural process is echoed in various forms, such as the erosional features seen on Mars that suggest the possibility of liquid water flow, or historical examples like the cliff-dwellers using balancing rocks as a defense. Overall, the importance of water in shaping landscapes is ubiquitously observed, from natural river courses to human-modified channels and lakes.