[1] The north-western part of the Ljósufjöll volcanic system has hyaloclastite hills and lava flows about 3–6 km (1.9–3.7 mi) wide.

[1] The fissure swarm widens to the south-east and extends towards the Haffjarðará river and the town of Bifröst at the eastern base of the peninsula.

[3] The belt has relatively low geothermal gradients for Iceland at about 40–60 °C/km (120–170 °F/mi) and erupts alkalic to transitional basalts, [3] with the Ljósufjöll system tending to be less alkalotic.

[1] In this region of the system to the east, the younger basaltic formations often do not entirely cover the older Neogene basement rocks.

[3] This must have had magma that evolved in two different storage zones, presumably one in the lower crust and one in the upper-mid-crust so as to be consistent with other findings in the Snæfellsnes volcanic belt.