Black Bay is one of Grenada’s black sand beaches located off the beaten path in the parish of St. John. Accessible via a 20-minute hike from the Concord main road, this small beach is situated in a secluded spot. In fact, on a regular day, you will most likely be the only one there enjoying the glittering sand and warm water.
Black Sand
There are two types of black sand beaches; one where the grains are very sharp and one where the edges have been rounded over. It's how the lava enters the water that causes the different beach types. When it flows directly into the water it is still very hot (anywhere from 750 to 1,250 degrees Celsius). Contact with the cold water shatters it into small shards. These pieces are either deposited right there, or are carried, for a short distance, along shore by the currents and then deposited. In this case the grains will be very sharp.
If a stream cuts through an older lava bed it will break down the lava into smaller pieces but these will be more rounded since the water action is bumping them around against each other and the ground. That action is like sandpaper grinding off the sharp corners. Also, if the lava pieces are transported by the ocean currents for a long distance (kilometers) any sharp edges will be worn off in the same manner. So…you have lava, hot or otherwise, entering the water, either being beaten up by the currents or being immediately deposited to form a beach.
Wentworth scale
The Wentworth Scale consists of a logarithmic scale of size classification (larger diameter) of clastic sediments fragments (or detrital), the thinnest to the thickest, created in 1922 by CK Wentworth. This scale is often used by geologists and their classification usually differs slightly from those made by the engineers.
Rocks and sand
Tipical grain sizes are:
Clay (<4 mm),
Silt (>4 mm - <64 mm),
Sand (>64 mm <2mm),
Bead (>2 mm - <4mm),
Pebble (>4mm - <64mm),
Cobble (>64mm - <256mm)
Boulder (>256mm).
Sands of properties
The color that the sands have relates much with its mineralogical composition. Thus, the silica sands are white when pure, as well as calcareous sands. The basaltic sand are black as well as those that are rich in organic matter or magnesium compounds. Iron compounds give the sands yellowish or greenish. The sand mainly composed of quartz grains, due to the hardness given by this mineral, scratching the glass and steel. They are unassailable by acids and are practically insoluble in water. Sand: Dune Environment The grains making up these sands are lightweight (are transported by wind), well calibrated (all have the same size) and rolled. They have scores and dull surface due to clashes with other grains. Quartz grains present since they are easily transported by wind.
To log this cache.
To get to log this cache you will have to visit and answer the questions which are related to the coordinates given the earthcache.
When answers are collected, send them to CO for verification.
You can log immediately after answers are sent CO. If there are any questions about your answers CO will contact you.
Logs without answers to CO or with pending questions from CO will be deleted without any further notice.
Questions:
1. Answer the questions under by visiting the given Coordinates.
A. At the posted coordinates, pick up a handful of sand and describe what you see:
- Are the pieces round or angular?
- Would you say this sand is fine, medium, coarse, or very coarse? (think in terms of sand paper)
- What colors do you see and why do you think these colors are present?
- Does it feel heavier or lighter than "traditional" sand?
B. Use the magnet. Is this black sand magnetic? If yes, explain why?
C. Visit both ends of the beach (see waypoints 1 & 2)
- What kind of rocks do you see at each waypoint ?
- Why is there such a difference between both waypoints?
2. Take a photo of you (face showing is not mandatory) or your gps from the location without revealing answers.
The picture must include your geocaching name (written on a piece of paper, on your phone / tablet, on your t-shirt, on your body, whatever).
If you visit this cache as "team", each photo needs to be with your own nick-name. Logs with team nicknames are not permitted and will be deleted.
These requirements are there to ensure you actually went to Black Bay Beach after this cache has been published. Re-using old vacation pictures is not permitted.
Any log that doesn't meet the requirements will be deleted!
Enjoy the beach and have fun.
Happy Caching!