The point-to-point distance was only 26.8 meters (88 ft), but the path covered 127.4 meters (418 ft). I’m assuming they were gathering data with the RIMFAX instrument.
RIMFAX is a ground-penetrating radar on the rover, it uses radar waves to see geologic features under the surface. The device can make detections perhaps dozens of meters/yards underneath ground, such as for buried sand dunes or lava feature, or in this case maybe they were identifying the underlying strata that formed these delta deposits.
Not of this measurement, but there are some from earlier in the mission when they were on the crater floor. Instrument data is normally released about 6 months after it was acquired.