Rocky Road Cake

INGREDIENTS

• 1 1/2 cups all-purpose flour
• 1 cup white sugar
• 1/2 cup unsweetened cocoa powder
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 5 tablespoons vegetable oil
• 1 teaspoon vinegar
• 1 teaspoon vanilla extract
• 1 cup water
•  
• 2 (1 ounce) squares unsweetened chocolate, chopped
• 1/4 cup margarine
• 1/4 cup water
• 2 cups confectioners' sugar
• 1 cup miniature marshmallows