Dear Ramanaduli,
You are correct in a way. Periya Puranam does not give
more details about the dance she witnessed at Tiru Alangadu,
which is of course, the Ratna Sabha, the Court Hall of Ruby.
But Karaikal Amma has sung a few songs which find place
in Book XI of 12 Books of Saiva Canon. There she says
in one decad titled Tiru Alangadu Mootha Tirupathigam,
the Elder Decad of Tiru Alangadu, that she is hearing the
sound of Siva's anklets, she is seeing His third eye, she
is seeing the serpants on his body, the Ganga roaring on
his matted locks, the crescent moon, which is afraid of the
serpents, the laughing skulls of many a crore of Brahmas
on his shoulder and on his palm. These are all mystic visions.
People with faith believe them, that is all. Saiva Siddhantam
says that after every 100 Brahmas die, one Vishnu dies. Like
that several crores of Brahmas and several lakhs of Vishnus
have met with death. But Siva is beginningless and endless.
Manikkavachagar also says this in Tiruvachakam. Sri Sankara
says in Sri Soundarya Lahari: "When Brahma, Indra and Vishnu and all devas close their eyes one by one and die, You {Lalita}
are playing with Siva in the garden of Kailas!"
Arunachala Siva.