Temporal Drift

Temporal Drift is the technical name for the time differential between Earth and Altierra. There are few data points but enough to show that the differential is variable, both in a single portal and between the two.

The Tierrapuerta

The original portal between Patagonia and Alta had only one temporal data point. When the Spanish settlers passed through the portal, it was in 1585 Earth-reckoning, six years after the English had entered in 1579. The time difference in Altierra was 177 years however.

Because there is only one data point, it is impossible to see how time passes between the two worlds, whether it is logarithmic as in the Mundumbra, or a simple line.

The Mundumbra

There are a few more data points with the Mundumbra between Dartmoor and Isla Arbojan which shows that the time differential varies over time, In the short time, Altierran time is longer than Earth time, but this reverses about 3 years (where the time is the same with both).

Emily visits Altierra

The first data point in The Snow Beyond the Wall is when Emily enters Altierra and returns, looking for help for Meg who has been captured.

Earth Time	Alt. Time	Event
10.25	13.00	Emily passed through the portal into Altierra
10.40	13.55	Emily returns to Earth

So 15 minutes of Earth time is equivalent to 55 minutes in Altierra.