Shania would be unable to determine the oldest formation because there is no key on the map. The map does not contain the proper details to be used to infer age relationships among the formations.
A map presents a three dimensional world on two dimensional paper or surface.
To infer relative ages, a cross section from the two dimensional representation is the most desired.
From the cross section, the third dimension can carefully be studied and ages inferred.
There is little to no way we can infer relative age relationship on this surface.
To do that, we would require a key. Most times, the key shows the stratigraphic column which puts rocks in their correct ages.
Most keys are arranged with formations from the oldest at the bottom and the youngest on top.
Since this map lacks a key, direction, scale and other map elements, it would not be possible to infer relative ages of the rock.
