Jill Layfield left Backcountry.com on Dec. 10 as chief executive, after four years at the head of the American company, giving no reasons for her departure. A replacement has not yet been announced, but Jim Holland, a co-founder of Backcountry.com and her predecessor, remains as president. Since joining this e-commerce site for outdoor products based in Salt Lake City 11 years ago, Layfield played a strong role in its development, contributing to lift its sales from $30 million to $500 million, including the sales of five other websites. One of the moves performed under her management was the acquisition of Bergfreunde.de in Germany. Last July, the group was sold by Liberty Interactive Corp. for $350 million to a private equity company, TSG Consumer Partners.