The enormous gams, like everything else in rural Texas, are cordoned off by endless barbed wire, but visitors can read all about them on a nearby Texas Historical Marker. The marker cites Shelley's poem, describing "two vast and trunkless legs" and "near them… half sunk, a shattered visage."
A thoughtfully placed asterisk directs readers to a footnote explaining why the stumps before them accompany no such shattered visage. The visage, "(or face)" the plaque helpfully explains, was apparently damaged by students from Lubbock after they lost to Amarillo in an unspecified competition. The face now resides, the footnote adds, in the Amarillo Museum of Natural History.
Of course, you have to realize the man behind the whole thing is the same person who was described in a 1999 poll as both a "subversive genius" and a "ridiculously foolish eccentric." It turns out the historical marker is a sham, the big face doesn't exist and Amarillo has never had a museum of natural history.
Quite simply, as Marsh has pointed out, Shelley's poem is about the futility of monuments. So, he built a monument to it.