This photograph shows an iron formation.How does it form?
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 an iron formation.How does it form? 
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

Iron formations typically form through the precipitation of iron oxide minerals from seawater early in Earth's history, when the ocean was rich in dissolved iron. These minerals accumulate over time to form banded iron formations, such as the one shown in the photograph.

This Photograph Shows an Iron Formation