18 Pa.C.S.A. §3122.1.  Statutory sexual assault.

(a)  Felony of the second degree.–Except as provided in section 3121 (relating to rape), a person commits a felony of the second degree when that person engages in sexual intercourse with a complainant to whom the person is not married who is under the age of 16 years and that person is either:

(1)  four years older but less than eight years older than the complainant; or

(2)  eight years older but less than 11 years older than the complainant.

(b)  Felony of the first degree.–A person commits a felony of the first degree when that person engages in sexual intercourse with a complainant under the age of 16 years and that person is 11 or more years older than the complainant and the complainant and the person are not married to each other.