Stocks or plutons are small irregular intrusions Batholiths are usually granitic and cover hundreds or thousands of square kilometers. In the above diagram, non-batholithic rocks are shown in light blue. Geological cross-sections often show batholiths as extending downward indefinitely. In fact, geophysical techniques and field observations suggest that most batholiths are thick lenses 10 km thick or so. Many batholiths have some of the former roof rocks still present as roof pendants .
Most batholiths are composite and actually composed of many smaller intrusions, as shown here.