Anamation from Internet Geography

Introduction: Coastal landforms are some of the most beautiful geologic feature in Hawaiian islands.  Coastal landforms are varied along the shores of the big island Hawaii. In locations where active lava flows are present, the effects of the waves against the coastal cliffs are fresh and can be spotted easily.  These features form in a progression, going from cave to arch and ending in stack.

Caves (Coastline off of Chain of Craters Road near the active lava flows)

Eroded into: Surrounded by basaltic rock

Explanation: Waves crashing into a sea cliff will erode away the less resistant and weaker rock creating a cave in the side of the cliff.

Sea Arches (Coastline off of Chain of Craters Road near the active lava flows)

Eroded into: Basaltic Rock

Explanation: Arches are formed by the beating of waves along a sea cliff and the erosion of the less resistant and weaker rock. Where the waves present cannot reach the top of the cliff the rock is still attached to form an arch.

Eroded into: Basaltic Rock

Explanation: Isolated bodies of rock off the coast began as part of a sea cliff and were eroded by strong waves. The less resistant rock erodes away first forming a "stack" of rock in the water. Sea stacks may begin as a sea arch.

For a more simplified visual walkthrough of these explanations refer to the pictures and summaries on the right.

Pictures and explanations on the right are from Internet Geography. 

Albion College geology students and professors created these web pages as a follow-up to our March 2003 Geology 210 Regional Field Geology class trip to Hawaii.  The images, except where noted, are a product of our trip.  We make them available for non-profit, educational uses.  As a condition of use, we request that you inform the page author or Thom Wilch.  Thank You. 

This picture is showing waves attacking a weakness in the headlands.

From: Internet Geography

As waves attack a weakness an opening begins to grow and a cave is formed on the sea cliff. 

From: Internet Geography

Arches are formed by the continuous growth of sea caves.  Many times arches form by the meeting of two sea caves.

From: Internet Geography

The roof of the arch eventually becomes weak enough that it will collapse and become a sea stack.  Sea stacks are tall, steep sided islands near shore. 

From: Internet Geography

Stumps are the eroded remnants of sea stacks.

From: Internet Geography

Some of these coastal landforms can be seen here though this is not the best picture.  This is about the best we saw on our trip

Picture By: Thom Wilch