It's simply open-air precipitated calcium carbonate that had been dissolved by the depositing stream water in its flow underground in limestone.
The main types of limestone are chalk, coral limestone, travertine, and tufa. Chalk is soft and white, coral limestone contains coral and other marine organisms, travertine is formed by hot springs, and tufa is a porous rock formed by calcium-rich water.
The verb form of "climate" is "to climatize" or "to acclimate."
The verb form of erosion is "erode".
The most common form of hydrogen is in the diatomic molecular form, H2.
The verb form of geology is "geologize."