Siltstone, Tung Ping Chau

The sedimentary rocks of Tung Ping Chau consist mainly of siltstone and mudstone, which contain fossils of pollen, trees, and insects brought down from shallow inland streams. Fine and light sediments do not require high-energy hydraulic transport, suggesting that the deposition process was relatively calm, accumulating into thin layers of stratification. The stratification resembles the pages of a book, hence the name shale. Because the shale resembles thousand-layer cake, it is also known as “Thousand-Layer Rock.”