Combine first 4 ingredients in a large bowl. Cut in butter with a pastry blender until mixture is crumbly. Gradually add buttermilk, and stir with a fork until a soft dough forms.
Turn dough out onto a lightly floured surface; pat dough into a 1-inch-thick disk. (Dough will be sticky. Dust hands with flour as needed.) Cut disk into 8 wedges. Place wedges on a lightly greased baking sheet.
Bake at 425° for 13 to 15 minutes or until bottoms are golden and tops are lightly browned. Remove to wire racks to cool.