This photograph shows chalk.How is it formed?
A)evaporation of water in a lake or sea
B)accumulation of microscopic organisms composed of calcium carbonate
C)precipitation from seawater early in Earth's history
D)accumulation of silica-rich organisms or mixing of seawater and groundwater

Question

This photograph shows chalk.How is it formed? 
A)evaporation of water in a lake or sea 
B)accumulation of microscopic organisms composed of calcium carbonate 
C)precipitation from seawater early in Earth's history 
D)accumulation of silica-rich organisms or mixing of seawater and groundwater

Quizplus · Accepted Answer

Chalk is mainly composed of microscopic organisms such as coccolithophores and foraminifera, which accumulate and eventually form sedimentary rocks over time. These organisms are composed of calcium carbonate, which is also the main component of chalk. Evaporation of water in a lake or sea (option A), precipitation from seawater early in Earth's history (option C), and accumulation of silica-rich organism or mixing of seawater and groundwater (option D) do not typically result in the formation of chalk.

This Photograph Shows Chalk.How Is It Formed