ENTER the park on the north side of the 79th Street transverse, walk west and pass under Greywacke Arch. On the far side, take the first left turn and continue south until you are brought to a jarring stop by a scowling bully who brandishes two swords and totally disrupts the tranquil atmosphere of a pastoral park. His horse, as least, has the grace to look embarrassed.

Directly across the path is a curious looping design in which a tiny plot of grass is hemmed in by paving. The pattern may symbolize the Park Department's infatuation with asphalt. It is apparent that greenery comes in a poor second.

The east end of Belvedere Lake with the heavily grooved outcrop in the foreground.

The sloping shelf at the water's edge displays the broadest glacial scars to be found in the park. The central and largest one looks like the mark of a tugboat drawn over a sandbar. Even granting the enormous force of a moving ice sheet 1,000 feet thick, it must have taken a vast number of boulders to gouge channels of such exceptional size. As a basis for speculation, we may imagine that Vista Rock, the massive outcrop on the southwest side of the water, may have extended considerably farther north before the glacier and subsequent erosion whittled it down. If so, its bulk may have deflected a portion of the glacier's sole and sent a doubled cargo of rocks to grind over the outcrop at our feet.

On the far side of the meager pond, wistfully titled Belvedere Lake, the enchanting Belvedere Castle crowns Vista Rock. It is the most endearing of Olmsted and Vaux's creations, a distillation of fairytale, history and legend. It is Tintagel or Camelot, Elsinore or Dunsinane; on a misty evening at sunset, you may glimpse Rapunzel letting down her yellow hair from a turret window. This imaginative delight is falling into ruin for lack of maintenance which is lavished instead on the sleazy theater below, a structure that flaunts its entrails in the air and is gaudily painted to intensify its assault on the landscape.

It's a long time between glaciers.