They spent two days at the edge of the ice cap on Ellesmere Island. Harry checked his perceptions at different locations and recorded the complete coding sequence.
Cassandra found several simpler sets of incised marks on a moraine ridge. They consisted of only a few short, parallel lines, similar in style to the marks near the North Pole but simpler.
She sketched the marks and added them to her notebook.
On the evening of the third day, the Technical Group's final reply arrived: the structure on Ellesmere Island was confirmed as an early variant of the original structure at the North Pole, with simple coding, a low frequency, and a long cycle. They recommended including it in long-term monitoring and treating it as the second node in the network's developmental sequence during analysis.
"Then the order in which the whole network developed is clear." Harry read through the Technical Group's reply. "The North Pole came first, Ellesmere Island second, northern Baffin Island third, Greenland and Iceland fourth, and Norway last. The main system might have been built latest of all, or it might be another branch from the same period."
"Then this network's history could span over a thousand years," Cassandra said.
"Or even longer." Harry looked at the distant ice cap. "Each generation of builders expanded and improved on what their predecessors left behind, eventually creating the entire network we see today."
They spent another day on Ellesmere Island, collecting continuous monitoring data.
The Technical Group approved the monitoring plan and established a permanent monitoring station at the edge of the ice cap.
"Then we can wrap up this investigation," Isabelle said.
Harry stood at the northern tip of the island, watching the distant gray-white ice field gradually blur in the twilight.
Cassandra walked over and stood beside him.