CLAMP is a method of obtaining ancient climate information from the architecture (physiognomy) of fossil leaves of woody dicot flowering plants.

It can be applied to any fossil assemblage up to almost 100 million years old where there are at least twenty different morphotypes (species) preserved, and where evidence suggests that the assemblage is likely to be a fair representation of the leaves present in the ancient source vegetation.

Such palaeoclimate proxies are important in quantifying past climate change in order to better predict and plan our future.