Complex sentence: In 1898 Fernow left the Division of Forestry to become the first dean of the New York State College of Forestry at Cornell, the first four-year forestry school in the United States.
Split into simpler sentences: In 1898 Fernow left the Division of Forestry to become the first dean of the New York State College of Forestry at Cornell. The program was the first four-year forestry school in the United States.