Well, the hill or small mountain was produced by forces deep inside the earth that caused parts of the earth's crust to rise while others sank. As the crust would rise, combined with erosion by water, ice, and air over millions of years, can explain what happened here. These types of erosional mountains or hills are also assisted by rivers that have helped carve them as well as continental drift, plate tectonics, and sea-floor spreading to help answer the question. Is this the answer you were looking for?