The Permian Period (230 to 280 m.y. ago) dawned with renewed rising of
the highlands in northern New Mexico and southern Colorado. Floods of
red sand and clay, washed from the rotting hills, wiped out the seas of
northern and central New Mexico, and intertongued southward with marine
limestones. These early Permian rocks are the Hueco Limestone near El
Paso, there 2200 feet thick, the Abo Redbeds near Albuquerque, and the
upper Sangre de Cristo Redbeds southeast of Santa Fe. Wherever the
redbeds crop out, their dark reddish brown hue, speckled and striped
with spots and streaks of green, enlivens the drab gray-and-brown
landscape. Some of the reddish coloring is from angular grains of red to
orange feldspar, but most is in thin brilliantly tinted skins of
hematite that coat the sand grains and saturate the clays. In northern
and central New Mexico, amphibians and other primitive vertebrate
animals lived amid the red soils and sands; their bones and imprints
have been preserved on thin flat slabs of sandstone that now decorate
sidewalks and patios.