HUCKLEBERRY RIDGE TUFF OF YELLOWSTONE GROUP (AGE SLIGHTLY MORE
     THAN 2 Ma)--Lavender to gray-brown welded rhyolite tuff. Thr
HEART LAKE CONGLOMERATE--Abundant gray limestone and dolomite clasts and sparse
     rhyolite and quartzite class in a talc and clay matrix. Thl
SHOOTING IRON FORMATION--Greenish-gray to pink tuffaceous lacustrine and fluviatile
     claystone and siltstone, fine-grained sandstone, and conglomerate. Tsi