LR is where we initially saw these dikes.

DIKES: Many visitors are curious about the "ribbons" that run through the rocks at Joshua Tree. These are dikes and veins and though they look very similar, these features have very different origins.
Dikes are formed when magma fills in a fracture in a pre-existing rock. They are typically large, extensive, and continuous features that are tabular in shape. At Joshua Tree, many of the dikes have a similar composition to the monzogranite.

Veins look similar to dikes, but are often smaller, thinner, and more randomly distributed. They form from the fluids that remain after an igneous pluton has nearly solidified. By the time most of the granite has cooled and solidified, the remaining magma is very fluid rich. This fluid may contain concentrations of rare elements. The fluid circulates through gaps and cracks in the solidifying granite. Eventually, the fluid itself cools enough to solidify and fill the open space in the newly formed rock.
Dikes and veins can be found anywhere in the park where monzogranite is found. The Skull Rock Trail is a great place see these features and trace their path across the landscape.