Welcome to Sunset Point, I think you will agree it is an amazing place at any time of day.
Once you take you eyes of the view and look a little close at the immediate surroundings it wont take long for you to notice why we chose to leave an Earth Cache here.
The locals refer to the rocks here as ‘Shell Grit’, it is easy to see why. What we are actually seeing here are ‘New Rocks’, I know we usually think of rock as a Millions of years old and we don’t really think about the fact that new rocks are constantly being formed.
Beachrock is a friable to well-cemented sedimentary rock that consists of a variable mixture of gravel, sand, and silt-sized sediment that is cemented with carbonate minerals and has formed along a shoreline. Depending on location, the sediment that is cemented to form beachrock can consist of a variable mixture of shells, coral fragments, rock fragments of different types, and other materials. It can contain scattered artifacts, pieces of wood, and coconuts. As an example of how ‘young’ Beachrock really can be there have been cases where man made items such as plastic bottle caps and drink cans have been found cemented into Beachrock. Beachrock typically forms within the intertidal zone within tropical or semitropical regions.
On retreating coasts, outcrops of beachrock may be evident offshore where they may act as a barrier against coastal erosion. Beachrock presence can also induce sediment deficiency in a beach and out-synch its wave regime. Because beachrock is lithified within the intertidal zone and because it commonly forms in a few years, its potential as an indicator of past sea level is important.
Beachrock units form under a thin cover of sediment and generally overlie unconsolidated sand. They typically consist of multiple units, representing multiple episodes of cementation and exposure. The mineralogy of beachrocks is mainly high-magnesium calcite or aragonite. The main processes involved in the cementation are: supersaturation with CaCO3 through direct evaporation of seawater, groundwater CO2 degassing in the vadose zone, mixing of marine and meteoric water fluxes and precipitation of micritic calcium carbonate as a byproduct of microbiological activity.
Beachrocks are located along the coastline in a parallel term and they are usually a few meters offshore. They are generally separated in several levels, which may correspond to different generations of beachrock cementation. Thus, the older zones are located in the outer part of the formation when the younger ones are on the side of the beach, possibly under the unconsolidated sand. They also seem to have a general inclination to the sea (50 – 150). There are several appearances of beachrock formations, which are characterized by multiple cracks and gaps. The result from this fact is an interruptible formation of separated blocks of beachrock, which may be of the same formation.
The length of beachrocks varies from meters to kilometers, its width can reach up to 300 meters and its height starts from 30 cm and reaches 3 meters.
Following the process of coastal erosion, beachrock formation may be uncovered. Coastal erosion may be the result of sea level rise or deficit in sedimentary equilibrium. One way or another, unconsolidated sand that covers the beachrock draws away and the formation is revealed. If the process of cementation continues, new beachrock would be formed in a new position in the intertidal zone. Successive phases of sea level change may result in sequential zones of beachrock.
To log this Earth Cache we require you to wander around and look at the area, consider the information given and perhaps if you need to do some research of your own, then message us with the following answers to the best of your ability;
1. What does the position of the Beachrock here suggest about the area over time?
2. Find an embedded shell, examine it, and tell us what type you think it might be, is this rock very hard or soft and crumbly? What do you think that suggests?
3 There are lots of little tiny tracks in the sand amongst the broken pieces of rocks, if you are there at the right time of the day you might find the culprits, if not you might be able to guess or follow one of the tracks to find out who made them?
4. A photo of your team or GPS near GZ. (Optional)
You are welcome to log your answers straight away to keep your TB's and Stats in order but please message us with your answers within 24 hours. Cachers who do not fulfil the Earth Cache requirement will have their logs deleted.
Source: Wikipedia,,
