The coincidence of inter-layered formations of shale and sandstone/conglomerate, their northwesterly aligned folded structure, the eroding power of southeasterly moving glacial ice and the modern southeasterly or northwesterly directed wind-driven waves and storm patterns have resulted in the prominent northwesterly-southeasterly alignment of the Gulf Islands.
Throughout these beautiful islands the prominent headlands and high ridges are formed from comparatively erosion-resistant sandstone/conglomerate whereas the narrow bays and valleys are sculpted from softer and more easily eroded shale.
Different types of rocks respond to weathering and erosion in different ways.
