Assistant Professor of History Patricia Nelson Limerick will teach her last classes of the popular History 1609b. "The American West, 1850-1950," and History 7lb. "Modern America," this spring.

She has accepted an offer to teach at the University of Colorado and will move to Boulder after she takes a year off to write a book about American frontier history.

Limerick said yesterday she expects to teach a Western history course similar to History 1609b and that she will probably be offered tenure after spending some time at Colorado teaching and researching.

She said she is leaving because she doubts she would receive tenure at Harvard in the near future, explaining. "It's been over 10 years since [Harvard] directly promoted someone in the History Department."

But she said she will spend the next year here writing her second book, tentatively titled. "The Burdens of Western American History." Her first book, "Desert Passages," has been completed but not yet released.

The University of Colorado made its offer to Limerick last December after spending two years searching for a replacement for a retiring History professor. Boyd Hill, chairman of the Colorado History Department, said yesterday.

"Limerick made a very dynamic and impressive presentation of herself and her work," he added.

The History Department here is currently looking for two new American history professors. Stephan A. Thernstrom, Winthrop Professor of History, said yesterday. But he added that neither would necessarily specialize in the West.

History 1609b will probably not be offered next year, Limerick said.