Sita ji had brought a hand full of sand from the other side of Gangaji.
From it she had made a raw model (Kuri) of Lord Shiva and
worshipped that. Later, the temple of Lord Shiva was built here.
Valmiki Ramayan 2/52/92, 93 Manas 2/101/1 to 2/103/1; 2/104 doha