Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
SOREL
As described in historical dictionaries
Patronymica Britannica (1860)
SORE. SOREL. " A sta? of four years old is called a sore, and of three a sorel ; and so named from their colour." It lias been explained as sib-i'iifis, nearly, or approaching to, red. Richardson.