Book 12 Hymn 1 of the Atharvana Veda is called the Bhumi Sukta, and it's dedicated to Bhumidevi the goddess of the Earth. Here is what one of the verses says:
- She whom the Asvins measured out, o'er whom the foot of Vishnu strode, Whom Indra, Lord of Power and Might, freed from all foemen for himself, May Earth pour out her milk for us, a mother unto me her son.
Now the "foot of Vishnu" is clearly a reference to Vishnu's incarnation as Vamana the dwarf, where one of his steps was on the earth. And I think the reference to Indra and the foemen is probably an allusion to the story of Indra's defeat of the demon Vritrasura, which is Indra's most celebrated deed in the Vedas.
But my question is, what is the story of the Ashwini Kumaras "measur[ing] out" the Earth? For those who don't know, the Ashwini Kumaras are the twin sons of Surya the Sun god and his wife Sanjana, who had taken the form of horses at the time; see the passages quoted in my answer here. They are the gods of the morning and evening star, as well as gods of medicine. People today mostly know them for their role in the Mahabharata as the fathers of the Pandavas Nakula and Sahadeva. And in the Ramayana, they were the fathers of the Vanaras Mainda and Dvivida (who ironically fought their brother Sahadeva, as I discuss in this answer).
In any case, are there any other scriptures which describe the Ashwini Kumaras measuring out the Earth? And what does it even mean to measure out the Earth? Does it mean finding out how big it is?