thumb|The graphic presents the present-day annual mean surface omega calcite: the normalised saturation state of calcite. Areas with a value less an 1 indicate a likeliness for dissolution (undersaturated) while a value over 1 indicates areas less likely for dissolution (oversaturation).
The lysocline is the depth in the ocean dependent upon the carbonate compensation depth (CCD), usually around 5 km, below which the rate of dissolution of calcite increases dramatically because of a pressure effect. While the lysocline is the upper bound of this transition zone of calcite saturation, the CCD is the lower bound of this zone.
CaCO<sub>3</sub> content in sediment varies with different depths of the ocean, spanned by levels of separation known as the transition zone. In the mid-depth area of the ocean, sediments are rich in CaCO<sub>3</sub>, content values reaching 85–95%. As depth and pressure increases within the water column, calcite solubility increases, causing supersaturated water above the saturation depth, allowing for preservation and burial of CaCO<sub>3</sub> on the seafloor. However, this creates undersaturated seawater below the saturation depth, preventing CaCO<sub>3</sub> burial on the sea floor as the shells start to dissolve.
The equation
:<math>\Omega = \frac{ \left[\text{Ca}^{2+}\right] \left[\text{CO}_3^{2-}\right] } {K'_\mathrm{sp</math>
expresses the CaCO<sub>3</sub> saturation state of seawater. The calcite saturation horizon is where Ω = 1; dissolution proceeds slowly below this depth. The lysocline is the depth that this dissolution impacts is again notable, also known as the inflection point with sedimentary CaCO<sub>3</sub> versus various water depths.
The depth of the CCD varies as a function of the chemical composition of the seawater and its temperature. Specifically, it is the deep waters that are undersaturated with calcium carbonate primarily because its solubility increases strongly with increasing pressure and salinity and decreasing temperature. As the atmospheric concentration of carbon dioxide continues to increase, the CCD can be expected to decrease in depth, as the ocean's acidity rises.