Marjorie Chan peers at the layers of rock and dirt, covered by palatial houses built high on eastern benches of the Salt Lake Valley, that act as a geologic crystal ball.

To the University of Utah professor, unearthed fossils and patterns in rock formations are historic blueprints for Utah's future. The geologic timetables document a history of weather patterns, climate and previous repeated seismic activity."It shows us how things have evolved over time," she said. "Once you cover it up, you can't put the clues together in order to put the story of history together."

She worries those clues are being paved over by a growing urban jungle.

Chan says the demand for home construction on eastern mountain slopes in Salt Lake, Weber, Davis and Utah counties is wiping out the shoreline carved by the pounding waters of Lake Bonneville more than 100 centuries ago.

And the growing number of gravel pits to supply materials for I-15 construction - such as the proposed 50-acre gravel pit at the mouth of American Fork Canyon - also cut into geologic wonders left by the lake of the Pleistocene epoch.

"This valley is one of a kind," the California native said. "We don't realize what kind of gems we have in our own backyard. Because of that, I'd really like to see things stay that (undisturbed) way."

Lake Bonneville, once one of the largest lakes in North America, receded to become what is now the Great Salt Lake. The sand-and-gravel shores, looked at by construction companies as virtual gold mines for natural-resource extraction, are still roughly in the same form.

Chan says a good example is the prehistoric beach at the Point of the Mountain leading into Utah County. Remnant sediment from Lake Bonneville is being hauled away by the truckloads for construction, and rows of houses line the steep terrain.

"If they put houses up there, then (the shoreline) isn't so easy to see anymore," she said. "In our lifetime, that will be covered by houses."

Chan and U. geography professor Don Currey, who was attracted to Utah in 1970 to study the environment, would like to see geological artifacts preserved, much like wetlands and other animal habitats are kept safe from being paved over for commercial or residential developments.

Instead of stringent laws, though, they'd like to see more people recognize that geologic treasures are being unearthed and destroyed by urban comforts and recreation. The duo may apply for a grant from the National Science Foundation to study how public policy could protect earth-history resources.

For example, Chan wishes the owners of a golf course near Little Cottonwood Canyon would have recognized some stratified rock laid down by water before they covered it with a lush fairway.

Currey frets about urban encroachment on the glacial moraines at the mouths of Bell and Little Cottonwood canyons. He says the history of Lake Bonneville may end up like King Arthur's Camelot - a legend that can only be learned about by what is written.

"There needs to be an overall prioritizing when planning. We can't stop development in its tracks, but there has to be a rational process," he said.

Preservationists know, however, that when money talks, developers listen. Private land will continue to be claimed by hillside houses as long as there is a market, and local governments can only do so much with zoning requirements to slow high-density construction or natural resource excavation.

As a result, quick drives around town have proven useful in quests to study the Earth, Chan said. Backhoes carving foundations for new houses or buildings are making temporary outdoor laboratories for geologists looking for a cross-section of the sediments and other deposits from the ancient lake.

Chan says a good site for geological study is the chasm for the foundation of oil magnate Earl Holding's proposed Little America Grand near 600 South and State Street.

She has taken her students there to look at the rock formations along the walls of the pit. The sedimentary layers can be studied to show how liquifaction induced by earthquakes impacted the landscape some 20,000 years ago.

Currey said gravel-pit operators at the Point of the Mountain have been cooperative in allowing groups to study carved out sections of the prehistoric beach.

Philip Emmi, a U. professor of urban and regional planning, suggests that establishment of a Center for Foothill Management Studies could benefit the Great Basin.

Such a scholastic center could inspect what ecological and geological harm is being done by building on eastern benches, as well as designing recreation and educational uses for the remaining shoreline, he said.

"There are many interesting issues surrounding foothill development," he said, adding that soil movement near hillside development has been a recent worry for some homeowners.

Still, how much harm can development cause in the name of progress? At one time, the shores surrounding Lake Bonneville were thousands of miles long - comparable to today's Lake Michigan. Even if the shoreline between Malad, Idaho, and Fillmore, Millard County, were lost, just a quarter of the rock formations would be gone.

And, as a gravel-pit spokesman said at a recent meeting in Highland, construction in Utah has created a "constant need for materials."

"At the rate we are going, we are depleting our resources," said Tom Case, a representative from Concrete Products Co., a firm hoping to open a new 50-acre extraction plant in the northern Utah County city.

"We work in an industry that no one wants in their backyards, but it is still wanted and needed," Case said.

Developers can argue that there are places that can still be studied, Currey said, but there are "gems" being threatened that he believes are irreplaceable.

"I don't think there's any way we, as the living generation, can evaluate the loss this would constitute to future generations," he said. "We should slow down this re-engineering of the Earth's surface and at least leave some of the decision-making to future generations."