Jack Road Dike - An Earth Cache EarthCache
Jack Road Dike - An Earth Cache
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The Sunshine Coast does not have a lot of geological phenomena but this dike near the foot of Jack Road is one of them. While dikes are not particularly common, they are not rare either. One just needs to keep any eye out for them.
Jack Road Dike
This dike is wide enough that it is very easy to observe at all but the highest of tides as it is located in the upper tidal foreshore area. A lower tide does offer the best viewing of it though. It is best to park at the intersection of Jack and Browning Roads and walk the 150 metres or so down a nice path to the cache site. While Jack Road continues towards the ocean, parking and turning space is very limited, hence parking is best at the suggested location.
Take the Pathway on the Left
A dike, in geology, refers to an intrusive igneous vein of rock and its horizontal width is usually considerably smaller than its depth or length. The width can vary from less than a centimetre to many metres and its length can extend to over many kilometres.
In slightly simpler terms, a dike is an intrusion or influx of molten rock between two existing layers of rock in a cross-cutting fissure or crack. This means that a dike cuts through other pre-existing layers or bodies of rock and that it is always younger than the rocks that contain it. Dikes are usually high angle or nearly vertical in orientation but subsequent tectonic deformation may rotate the sequence of layers through which the dike lies so that the latter could even become horizontal. These horizontal dikes between the rock layers are called intrusive sills.
Tectonic deformation can also cause horizontal deflections in dikes, such as is the case with this particular one. From the cache location given, the dike becomes visible as it appears from under the ground cover at the natural boundary of the ocean and it continues west for about 110 metres before disappearing. About half way along its length, there is a deflection to the north of about 10 degrees. At its western extremity, it is further down on the foreshore and becomes buried by the cobble stones on the beach.
Some photographs of the dike are included in the gallery and you will note that there are some very narrow ones and one much wider than the rest.
In order to complete the log of this Earth Cache, the answers to the two following questions must be emailed to sir.vayor@gmail.com
1. What is your estimated width of the widest dike?
2. What is the middle name of the person commemorated by the memorial bench at the cache location?
Unfortunately, anyone not answering the two simple questions above will have their log removed if the answers are not submitted with within 20 days. Three other geocaches worth visiting in the area are: GC1YFFX, GC1RE12, and GCHXD4.
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To learn more about earth caches and how to become an earth cache master, please visit: www.earthcache.org
Source information:
Various copies of my own notes and information from geology text books in my personal library.
Wikipedia.org and other websites.
Additional Hints
(Decrypt)
Rawbl gur cyrnfnag jnyx qbja gur cngu gb gur ornpu.
Treasures
You'll collect a digital Treasure from one of these collections when you find and log this geocache:
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