Preheat oven to 350 degrees.
Combine 2 cups flour, oats, sugar, baking soda and salt in large bowl.
Add butter, stir until all ingredients are moistened.
Reserve 1 cup crumb mixture.
Press remaining mixture onto bottom of ungreased 13 X 9 inch baking pan.
Bake for 15 minutes or until lightly browned.
Remove from oven and sprinkle with raisins and nuts.
Combine caramel topping and remaining flour in small bowl. Drizzle over base.
Sprinkle with reserved crumb mixture.
Bake for additional 20 to 25 minutes or until lightly browned.
Cool completely in pan on wire rack.