Why does sand not contain any gravel?

If sand contains gravel, it stops being sand, and becomes sand plus gravel. But of course that's not what you are asking. When minerals are eroded from rocks and transported as sediments, there are certain rules that apply. read more

If sand contains gravel, it stops being sand, and becomes sand plus gravel. But of course that's not what you are asking. When minerals are eroded from rocks and transported as sediments, there are certain rules that apply. read more

Again, both sand and gravel will work here. There are also other reasons to choose specific substrate such as using a plant-specific substrate or an aragonite/crushed coral substrate for raising pH. Gravel tends to be the standard for many people. read more

Sand and Gravel. Sand and gravel deposits found on beaches or in rivers and streams, are mostly quartz (silicon dioxide, SiO 2) grains. Weathering of rocks such as granite forms these quartz grains. In the process of weathering, the softer, weaker minerals in granite (such as feldspar) are weathered away. read more