NOTE: This Earthcache is only accessible by boat. The earthcache can be viewed from the ocean and all questions can be answers from this vantage point. There is no need to go ashore. However, if you decide to go ashore, please be advised that motorized boats can dock here only if they have a permit. Kayakers must anchor offshore where they will not damage the coral reef and must then swim to shore.
From GZ off the shore of Napali Coast, look about half a mile to the east to the west facing rock wall. It is hard to miss the large "marking" on this wall. A Native Hawaiian can most likely tell you a wonderful legend of Pele, their land, fire, nature and how this marking came to be. However, for this earthcache, we are going to stick to the science.
The distinct geolocial feature you are looking at is an igneous intrusion.
IGNEOUS INTRUSION
An intrusion is a body of igneous rock created under intense heat that has crystallized from molten magma. Igneous intrusions form when magma cools and solidifies before reaching the earth's surface. Three common types of intrusions are sills, dykes, and batholiths.
Sills - Sills form when mangma intrudes between teh rock layers forming a horizontal or gently sloping sheet of igneous rock.
Dykes - Dykes form as magma pushes up towards the surface through cracks in the rock. Dykes are vertical or steeply sloping sheets of igneous rock.
Batholiths - Batholiths are large, deep-seated intrusions (sometimes called plutons) that form as thick, viscous magma slowly makes its way toward the surface but seldom gets there.
To get credit for this earthcache message me with the answers to the following questions (do not post your answers in the log):
1. The name / GC code of the Earthcache
2. State whether this igneous intrusion is a sill, dyke, or batholith
3. Describe the general shape of the igneous intrusion. (One letter should cover it!)
4. Describe the color of the intrusion compared to the surrounding rock.
5. Guesstimate the height of the intrusion.
6. OPTIONAL: Post a photo of yourself with or near the intrusion.
References:
The Geological Society of London
The Australian Museum
*** FTF Honors go to STANDISHMAN for being the first to correctly answer all of the questions! ***