The first book on mudrocks was not published until 1964 . However , scientists , engineers , and oil producers have understood the significance of mudrocks since the discovery of the Burgess Shale and the relatedness of mudrocks and oil . Interestingly , the first book on mudrocks , named Geologie des Argils by Millot , was not published until 1964 ; however , scientists , engineers , and oil producers have understood the significance of mudrocks since the discovery of the Burgess Shale and the relatedness of mudrocks and oil .