[4] High-silica eruptions of the Tewa Group began about 1.85 million years ago and continued almost to the present day.

[5] The Polvadera Group is a sequence of basalt, andesite, dacite, and rhyolite flows that underlie part of the central and most of the northern Jemez Mountains.

The Lobato Formation is a sequence of mostly tholeiitic[7] basalt flows that underlies the mesas fringing the northern and northeastern sides of the Jemez Mountains.

[6] The earliest flows mapped as Lobato Formation are interbedded with Santa Fe Group sediments and have been dated at 14.1 + 0.3 Mya.

However, these are distinct in age and geochemistry,[9] and were assigned to the La Grulla Formation by Shari A. Kelley and coinvestigators in 2013.

The Rhyodacite of Rendija Canyon contains 11-16% phenocrysts of quartz and plagioclase, lesser amounts of sanidine and anorthoclase, and traces (<0.5%) of biotite, clinopyroxene, and hornblende.

The Dacite of Cerro Grande contains about 21% phenocrysts of plagioclase, hornblende, orthopyroxene, and subordinate clinopyroxene, with an age ranging from 2.88 to 3.35 Ma.

The lower flows include to 24% phenocrysts of plagioclase and hornblende with lesser amounts of quartz and biotite and traces of sanidine, orthopyroxene, and clinopyroxene.

The summit of Caballo Mountain is underlain by a relatively crystal-poor dacite containing about 2% phenocrysts of plagioclase and hornblende with lesser amounts of clinopyroxene and traces of quartz and orthopyroxene.

After about 2.88 Ma, Tschicoma volcanism shifted from the Sierra de los Valles eastwards to the western Española basin.

Here several small-volume dacite lavas erupted between 2.36 and 2.74 Ma that are now buried under the Bandelier Tuff of the Pajarito Plateau.

[17][8] The ages and chemistries point to five distinct batches of magma for the El Rechuelos Rhyolite as originally defined.

[17] The group was first defined by Bailey, Smith, and Ross in 1969 as part of their work establishing the stratigraphy of the Jemez Mountains.

[10] Obsidian obtained from the Polvadera Group has been found in Paleoindian archaeological sites as far east as Oklahoma.