The geology of the Kimberley coast is diverse, ranging from sandy plains on the Dampier Peninsular, to basalt intrusions, granites and the rocky sandstone cliff faces and steep gorges on the central Kimberley coast.
Approximately 2 billion years ago the Kimberley Plateau was formed when its underlying continent crashed into the Australian continent. This caused the uplifting of ranges, which were then eroded by an enormous river which carried sedimentary deposits to a shallow sea. These deposits became the Kimberley sandstones, siltstones and mudstones.
From 1.8 billion years ago, sandstone was laid down in several sequences, known as the King Leopold, Warton and Tertiary sequences. These Kimberley sandstones are up to 5km thick in parts.
Periods of uplifting then led to erosion, and huge outpourings of basalt, particularly around the Mitchell Plateau and Ord River Basin. Dolerite intrusions formed dykes, which are still evident in the King Leopold Ranges, and visible from Secure Bay, and on various islands along the coast.
During these turbulent periods of uplifting, volcanic activity pushed lava and magma into cracks in the sandstones, forming veins of crystalized quartz. The small island at the end of Hall Point in Deception Bay is an easily viewed example of geological layering.
Approximately 5 million years ago there was another period of uplifting and layering, followed by the drowning of the coastline approxiately 0.017 million years ago, forming the coastline as we now know it. Cyclone Creek in Talbot Bay is an excellent example of uplifting.
Further to the south, the Dampier Peninsular and areas around Broome consist of sandstones, mudstones and siltstones overlaid with pindan plains.