The soil type CA stands for "clayey alluvium". Clayey alluvium is a soil that is composed of fine-grained sediments that have been deposited by a river or stream. These soils are typically found in floodplains and other low-lying areas. They are often poorly drained and have a high water table. Clayey alluvium soils can be very fertile, but they can also be difficult to work with due to their high clay content.