If there is only one tetrahedral and one octahedral group in each layer the clay is known that the tetrahedral sheet becomes corrugated or twisted, causing ditrigonal distortion to the hexagonal array, and the octahedral sheet is flattened.
If there is only one tetrahedral and one octahedral group in each layer the clay is known as a 1:1 clay. Bonding between the tetrahedral and octahedral sheets requires that the tetrahedral sheet becomes corrugated or twisted, causing ditrigonal distortion to the hexagonal array, and the octahedral sheet is flattened.