Of the four base areas , only Alpental is located north of I - 90 .
Of the four base areas , only Alpental is is known for its advanced and backcountry terrain , including some of the steepest runs in the state .
Of the four base areas , only Alpental is located north of I - 90 and is known for its advanced and backcountry terrain , including some of the steepest runs in the state .