The crossword solution for the term 'Clay of the Past' is ALI. ALI is an acronym for Archaeological Landscape Investigation, which is a method used by archaeologists to study and analyze the landscape of a certain area. This method helps archaeologists to understand the past and how it has shaped the present. It involves looking at the physical features of the landscape, such as soil type, vegetation, and topography, as well as the cultural features, such as artifacts, monuments, and other evidence of human activity. By studying the landscape in this way, archaeologists can gain insight into the history of a region and its people.