Cross sections through large ammonite shells on a bedding surface. The outer chambers of the shells are filled with the muddy limestone which also surrounds the shells. The inner chambers were not completely filled with sediment: later, the remaining spaces were filled with crystalline calcite (white), precipitated from solution. Look carefully at the sediment between the ammonites - it shows abundant evidence of burrowing.
Scale: coin is 25mm across
Grid reference: 987 315