Mbh 12.69.4b

When the king relies upon only three of the four parts of the science of chastisement leaving out a fourth, the age called Treta sets in. A fourth part of unrighteousness follows in the train of such observance (of the great science) by three-fourths. The earth yields crops but waits for tillage. The herbs and plants grow (depending upon tillage). When the king observes the great science by only a half, leaving out the other half, then the age that sets in is called Dwapara. A moiety of unrighteousness follows in the train of such observance of the great science by half. The earth requires tillage and yields crops by half. When the king, abandoning the great science totally, oppresses his subjects by evil means of diverse kinds, the age that sets in is called Kali. During the age called Kali, unrighteousness becomes full and nothing of righteousness is seen. The hearts of men, of all the orders, fall away from their respective duties. Sudras live by adopting lives of mendicancy, and Brahmanas live by serving others. Men fail to acquire the objects they desire and preserve those already acquired. Intermixture of the four orders takes place. Vedic rites fail to produce fruits. All the seasons cease to be delightful and become fraught with evil. The voice, pronunciation, and minds of men lose vigour. Diseases appear, and men die prematurely. Wives become widows, and many cruel men are seen. The clouds do not pour seasonably, and crops fail. All kinds of moisture also fail, when the king does not, with proper attention to the great science, protect the subjects. The king is the creator of the Krita age, of the Treta, and of the Dwapara. The king is the cause of the fourth age (called Kali). If he causes the Krita age, he attains to everlasting heaven. If he causes the Treta age, he acquires heaven for a period that is limited. If he causes the Dwapara, he attains to blessedness in heaven according to the measure of his merits.