How did laccoliths create mountain groups such as the La Sal Mountains?

The La Sal Mountains and similar mountain groups, such as the Henry Mountains, were formed through the process of laccolith intrusion.

A laccolith is a type of igneous intrusion that occurs when magma is injected from a central, deep-seated pipe into the Earth's crust. This magma forces its way between existing layers of sedimentary rock, splitting the strata apart. Because the magma is viscous, it does not spread out thinly like a sill; instead, it accumulates to form a flat-floored, mushroom-shaped body that causes the overlying rock layers to bulge upward into a dome.

Each of these mountain massifs is composed of a group of these individual domed structures. Over time, the surrounding rock may be eroded, leaving the resistant igneous cores of the laccoliths exposed as distinct mountain peaks.123