Lord Shiva revealed to Brahma that the Shwet-kalpa derived its name from his complexion. “I took incarnation attired in white apparels. My complexion was fair. You being self-begotten were able to recognize me. Goddess Gayatri had also manifested from my body and later on became famous as ‘Shwet-Lohit-Brahm’.”
“The next kalpa was known as Lohit kalpa because of my red complexion, Goddess Gayatri had also incarnated in the form of divine cow. I became famous as Vamdev during this kalpa.”
Lord Shiva then went on to describe about the rest of the kalpas which had been named after his complexion. He also gave in-depth description of various subjects like, the different worlds, the vedas the four major castes etc.