Preheat oven to 350 F. Combine flour and sugar. Cut in margarine. Reserve 1 cup of this mixture for topping. Add cinnamon, soda, nutmeg and ginger to remaining flour mixture. Stir in eggs and buttermilk. (Do not use electric mixer.) Pour batter into ungreased 9- by-13-inch pan. Sprinkle the reserved topping over batter and bake in preheated oven for 45 minutes or until done. Serves 10 to 12.