Soil is formed from the weathering of rocks and minerals. The surface rocks break down into smaller pieces through a process of weathering and is then mixed with moss and organic matter. Over time this creates a thin layer of soil. Plants help the development of the soil.
In NSW it is a different story. It provides guidelines to parents and says a child aged 10-12 years can be left for up to 12 hours but not between 10pm and 6am. They must have a back-up adult available and can look after one or two other smaller children.
Below are general guidelines to follow when considering the age range for leaving a child home alone. 7 & under-Should not be left alone for any period of time. This may include leaving children unattended in cars, playgrounds, and backyards.3 to 15 years-May be left unsupervised, but not overnight. 16 to 17 years-May be left unsupervised (in some cases, for up to two consecutive overnight periods). It is important to note that no two children are alike, and parents must decide on a case-by-case basis what is best for their child.