Reference work entry
Wormkalk is a typical clastic limestone. It is usually in the form of thin layers composed of flat gravel particles with round or oval shapes in parallel arrays. In vertical cross-section, the gravels look like bamboo leaves; hence, it gets its name from the Chinese words as ‘bamboo leaf limestone’. A layer of yellowish or purple iron oxide rings is always present on the edge of the rock. Wormkalk forms in tidal flat beach areas with frequent tidal wave activity, and it is widely distributed in the Cambrian and Ordovician systems in North China (Fig. 15).
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