When will the Kalyug end? Are there symbols written in scripture?
Yes. According to MahAbhArata, the Kaliyuga ends with possibly total annihilation of mankind and then the mankind is regenerated with the Kritayuga (or Satyuga). During Vana Parva, Rishi Markendeya explains Yudhishtira about the effects of Kaliyuga. He also provides the signs of end of it.
... And when those terrible times will be over, the creation will begin anew. And men will again be created and distributed into the four orders beginning with Brahmanas. And about that time, in order that men may increase, Providence, according to its pleasure, will once more become propitious. And then when the Sun, the Moon, and Vrihaspati will, with the constellation Pushya 1, enter the same sign, the Krita age will begin again. And the clouds will commence to shower seasonably, and the stars and stellar conjunctions will become auspicious. And the planets, duly revolving in their orbits, will become exceedingly propitious. And all around, there will be prosperity and abundance and health and peace.
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