Trap rock

[2] The erosion of trap rock created by the stacking of successive lava flows often creates a distinct stairstep landscape from which the term trap was derived from the Swedish word trappa, which means "stairs".

[1] The slow cooling of magma either as a sill or as a thick lava flow sometimes creates systematic vertical fractures within the resulting layer of trap rock.

A major use for basalt is crushed rock for road and housing construction in concrete, macadam, and paving stones.

Well-known examples of outcropping trap rock include both intrusive sills and extrusive lava flows.

[6] Other prominent basalt ridges, mountains, buttes, canyons, and other landscape features include:

The East Rock trap rock ridge overlooking New Haven , Connecticut , U.S.
Trap rock forming a characteristic pavement, Giant's Causeway , Northern Ireland
Trap rock cliff overlooking the Hudson River from an overlook on the Hudson Palisades in Bergen County , New Jersey , U.S.
Trap rock forming a characteristic stockade wall, Giant's Causeway, Northern Ireland