The meaning of ‘A touchstone, a dashed track’

The meaning of ‘A touchstone, a dashed track’

The passage below is from Fathoms: The World in the Whale Hardcover by Rebecca Giggs.

Stand to one side a moment, to picture it: a seabird dawn, the departing ship faint on the grey horizon. Someone runs their thumb over the newfound text, its little notched serifs, the mystifying, sidewinding S in SHP. CONNECT-I-CUT rolls under their touch and they inquire of the word, its feeling as a sensation; a texture, a sculpture, an animacy. So Connecticut makes landfall soundlessly, dressed in the disguise of its anglicisation, having crossed an earlier border from Algonquian where once it was ‘Quinnehtukqut’ (meaning, ‘beside a long tidal river’). (A touchstone, a dashed track.) What the Yaburara thought, or said, on discovering these foreign incisions, is lost — not because of the attrition of time and memory, but as a result of the genocide and generational traumas that followed. Until microscopic analysis revealed otherwise, researchers suspected that the hatching action might have been the Yaburara striking out the whalers’ words; that the Indigenous petroglyph was an overwrite. But perhaps it was no epiphany to the Yaburara to hear it was the other way around.

I think I know the literal meaning of the bold-faced words.

(A touchstone, yardstick or standard, and a dashed track, a dotted line showing a track of an airplane)

But I cannot see why the author put those words in that context.

Thanks in advance.