The remnants of such clusters may be found in places such as the San Juan Mountains of Colorado (formed during the Oligocene, Miocene, and Pliocene epochs) or the Saint Francois Mountain Range of Missouri (erupted during the Proterozoic eon).
Os restos deles poden encontrarse en lugares como as montañas San Juan de Colorado (formadas durante o Oligoceno, Mioceno e Plioceno) ou nas montañas Saint Francois de Missouri (que fixeron erupción durante o Proterozoico).