Marine sediment’s – Sand

*****

The location:

Plakias is a village on the south coast of the Greek island of Crete. It is surrounded by mountains to the north and the Libyan Sea to the south. Around Plakias, phyllite quartzite determines the geology. The name in Greek means "flat", because the town stands on an alluvial fan of material that has washed down the Kotsifou gorge directly to the north. This material has formed along the sea's edge into a long, fine, gold-hued sand beach, which shelves very gradually out into the bay, making it quite safe for swimming and hence, for family holidays. Plakias is also known as windhole. There are winds here that whirl the sand around for days, which can be very uncomfortable.

***

Marine sediment’s:

Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor. These particles have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea. Additional deposits come from marine organisms and chemical precipitation in seawater, as well as from underwater volcanoes and meteorite debris. The movement of the water ensures that the stones are crushed and sand is formed. The constant movement grinds the big stones. This ongoing process makes for a sandy beach here. It's not just the water that plays a role. The frequent wind also contributes to this. Because the sand that is moved by the wind also works on the rocks and creeps small sediments. So several aspects contribute to the formation of sand here.

***

Sand:

Sand is a granular material composed of finely divided rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. The size of the sand particles varies. The surface is also very different. There are smooth, uneven and very sharp-edged surfaces. Ultimately, it depends on the composition of the rocks from which the sand or sand sediments were created. You need a magnifying glass to see these differences. But you can also make it visible in another way. There are subdivisions for the fineness of the sand according to their grain size. Due to the different surfaces, the sand also has different properties. We want to find out using the Earthcache.

***

***

If you let the sand trickle into a heap, taking into account the different surfaces of the sand, you will see differences. Here are a few examples and differences in materials:

***

Here are your tasks so that you can log this Earthcache (send us the answers by email or via the message center):

1. Take some sand from the beach, far from the water (dry) and pile it loosely (do not pack it) onto a surface. Use the tool to determine the number of degrees (see examples). What value do you get?

2. Same like No.1, but near to se sea - wet sand. Explain the differens between dry and wet sand.

3. Take a photo of your experimental setup and send it to us with your answers - don't put it into your log ! (Spoiler !)

4. Due to the number of degrees / gradient, the question arises, why is that so? What conclusions do you draw from this in relation to the surface properties of the sand on site? Hint: consider the sphericity, and how angular or round the particles are (reference the drawing, above). What effect does water have on the sand's angle of repose /degrees/gradient) ?

5. Compare the sand at the site with the fotos of (Sand examples...). Tell us the coordinates (example A1).

6. Take a picture of yourself on the beach and either send it to us or attach it to the log.

7. Optional: make a second "bunch" of something else (crazy things^^). Similar to No. 1 + No. 2 and describes your experiment to us. Also take a picture of this and attach it to the log :-) (fun !)

***

Help: it can be easier if you print out the tool before visiting the site. You can also show it on the mobile phone, but then you need another mobile phone or camera for the pictures. When you've done everything, you can feel free to log a found. If something is wrong, we will contact you. Logs without answers or spoiler images will be deleted without comment!

We wish you a lot of fun and enjoy this wonderful island with its friendly inhabitants 😊

KalimeraM & Patchwork-Rudel :-)

Sources: Wikipedia, crete environmental forum