People may seriously affect the natural scenario. Global warming - if, indeed, it is a real phenomenon - may prevent another ice age. "Remedial" work might prevent the falls from moving and changing. Technology will surely become more sophisticated a thousand or more years from now, and it will likely be possible to keep the falls as desired and still make it appear to be "natural."

But barring another ice age or human intervention, just how is nature planning to change Niagara Falls? Scientists seem to agree that there will be seven stages.

Stage 1

In about 2,000 years, the Horseshoe Falls will recede past the upper end of the Canadian Rapids and increase in height by about 55 feet, where it will capture the water from the American side of the river, drying up the American Rapids and Falls. Goat Island and the islands around it will become part of the mainland.

The Horseshoe Falls will get, barring any water diversion, all the water from the Niagara River. What a powerful cataract it could be!

Stage 2

In about 7,000 years, the level of the Chippawa-Grass Island Pool will go down, lowering the level of Lake Erie a little. At Navy Island, the Horseshoe Falls will split into two falls - the Tonawanda Horseshoe Falls and the Chippawa Horseshoe Falls.

Until it passes Navy Island, the Tonawanda Falls will get 70 percent of the water from the Niagara River, and the Chippawa Channel will get 30 percent.

Because of softer rocks on top of the Lockport dolostone, both falls will start decreasing in height as they recede past Navy Island. Each falls will follow the thalweg - the line connecting the deepest points of the bottom - in its channel.

Stage 3

The Tonawanda Horseshoe Falls will split, forming the Navy Island Horseshoe Falls. Buckhorn Island will then have a falls on each of its sides. The Chippawa Horseshoe Falls will continue to recede to the south. Each of the three falls will make its own gorge.

Stage 4

Having a lower bed, the Chippawa Falls will capture the water from the channel on the east side of Navy Island, drying up the Navy Island Horseshoe Falls and its gorge. This will give the Chippawa Falls all the water from the Chippawa Channel (60 percent of the water coming from Lake Erie). The Tonawanda Horseshoe Falls will continue to recede past Buckhorn Island.

Navy Island and Buckhorn Island will become part of Grand Island. The north Grand Island bridges will cross a gorge.

Stage 5

Both the Chippawa and Tonawanda Horseshoe Falls will become quasistationary (nearly unable to recede) at a height of about 50 feet, because water will be falling off Lockport dolostone into a pool with a bed made of the same hard rock. Steep rapids will form above the falls, as the softer shales and sandstone layers erode away often rather quickly.

Stage 6

Having a lower bed, the Chippawa Channel will capture the water from the Tonawanda Channel, drying up the Tonawanda Horseshoe Falls and its gorge. Grand Island will become part of the New York mainland.

The rapids in the Chippawa Channel will continue working their way to the south, and the gorge they produce will be more shallow to the south. The Chippawa Channel will now get all the water coming from Lake Erie, making it the Niagara River.

The Chippawa Horseshoe Falls will have moved very little.

Stage 7

A quasistationary falls will form between Buffalo and Fort Erie in 30,000 to 48,000 years. Water will be falling from Onondaga limestone into a pool with a bed composed of Bertie dolostone. The Buffalo/Fort Erie Horseshoe Falls will be less than 50 feet high. The Niagara River will then have two quasistationary falls with steep rapids between them and the great falls of the past will be a distant memory.

Paul Gromosiak of Niagara Falls is a local historian and author.