Preheat oven to 350F. In a large bowl, combine oatmeal, brown sugar, flour, and salt; mix well. Cut in the butter until the mixture is crumbly. Spread about 2/3 of the mixture on the botttom of a greased 8 x 8-inch baking dish. Spread blueberries over the mixture. Top with the remaining mixture. Bake for 45 minutes until bubbly. Serve warm with vanilla ice cream.