Most of its territory lies within the so-called Coastal Chain, which stretches from Hendaye to Zumaia. The entire coastal area (Punta Turrilla, Cape Higuer), including Jaizkibel (550 m), is made up of sandstones, microconglomerates, and marls (hard section; gypsum beds). On the southern slopes of Jaizkibel, there is a strip of land composed of limestones and marls (soft section; thin beds); this is followed by another strip, alternating limestones and sandy limestones with marls. The areas near the Jaizubia Canal and the entrance to the town are alluvial soils.