To Spring

 Set back in the woods, we recently hiked into a bit of a secret oddity that we hadn't visited in years...

A one-off large sandstone rock slab with embedded heavy-duty iron ring

A logical explanation: A bygone tether for a horse or a mule. Or for that matter anything that needed tethering back in the day (mining remnant). But why such a large and heavy-duty anchor which appears to be purposed more for hoisting the slab as opposed to mooring. And if so why is it not installed more toward the center of gravity of the slab to better balance the lift? Seems like it is only to be lifted as if hinged opposite end, like a trap door. And why lift the slab, anyway?

A fun explanation: The heavy slab is placed to conceal something beneath. A secret passage into the realm of the underworld? Could be. The slab is located directly within the elevation of the crop line of Loyalhanna Limestone, a soluble karst limestone deposit characterized by several local complex cave systems. And if placed to conceal, could it also be placed to retain something from getting out? The heavy iron ring could also be a reinforcing protective barrier against malevolent, "otherworldly" forces otherwise  contained, repelled or controlled by "cold iron".

We're stickin' with the latter.

Further corroboration:

"Zoogs are a race of sentient forest-dwelling creatures... they are mortal

enemies of cats, as they prey upon kittens and are preyed upon in return 

by adult cats... The Zoogs fear and shun a stone slab set with a huge iron

ring... this slab if opened reveals a path that leads down to the realm 

of  the underworld."

                                                                                    - Lovecraftian Lore

(Internet Image)

A Zoog as visualized by animator Richard ('Lone Animator') Svensson

We've yet to spot a Zoog anywhere near the slab.

A third alternative:

(YouTube Video)

'To Spring' (1936)

Happy Springtime