Sial has the following features:
1. It is the outermost layer of the earth as described by Suess.
2. The predominance of silica and aluminum is found in the composition of this layer.
3. The average density of this layer is 2.9 grams per cubic cm.
4. The depth of this layer is up to 50 – 300 km.
5. This layer contains the primacy of the acid content.
6. This layer provides different depths and reliefs to continents and oceans.
7. It is considered to be floating above the sima layer.