Examples from literature

• On this sand a great mass of boulder clay usually quite devoid of fossils was accumulated. 
• The boulder clay, when it was first studied, seemed in many of its characters so singular and anomalous, that geologists despaired of ever being able to interpret the phenomena by reference to causes now in action. 
• The chalk, then, is certainly older than the boulder clay. 
• The difficulty, moreover, of accounting for the entire dearth of marine shells in till is removed when once we have adopted the theory of this boulder clay being the product of land-ice.