Aeolian Dunes of Cedar Lake

Published Feb 12th 2015 in Geology & Activities, Daytrip, geology, sanddunes

Cedar Lake (Lagunas Sabinas) is a large salina (salt lake) in Gaines County. To the southeast and about three miles away is a small arc of sanddunes less than two miles long. The landowners of the dunes planted Hermelo Weeping Lovegrass on the dunes in the 1980s hoping to stabilize the dunes. Nearby areas of vegetated dunes are found. The 2009 class of the Master Naturalists were invited to tour two pieces of private property - one that had the open sand dunes, and another belonging to the family of Nathan Taylor, one of the students in the class.

The following photographs were taken by the various members of all three classes of the master naturalists 2007, 2008, 2009.

Hermelo Weeping Lovegrass is African in origin and in the early days of the Conservation Reserve Program (CRP) was planted extensively. It is a testimony to the water-holding capabilities of loose sand that the grass was able to germinate and survive.

The grass can even germinate on sheer faces on the dunes.

The temperature was 39 degrees F, and the wind was blowing 10-15 miles an hour, as the group of Master Naturalists listened to a brief talk about what might be found before the group broke up and headed in several different directions.

Even on top of the dunes harden crusts were found. This poses a mystery - how did they form? They were often only an inch thick. Was it the sign of previous organic material that had hardened with time and been left behind?

Wind and rain sorts the sand. The darker areas are organic material, while the palest lines are the smallest grains of sand.

Bedding (or layering) was visible on sheer faces of the dune. What causes the layers to form, and why do they remain visible. Also seen are the seedpods of cockleburs. Along with the lovegrass, cockleburs were the dominant plants of this small band of dunes. Cockleburs normally grow in areas with clay soil that hold moisture after a rain, but are also often common in the sanddunes.

The cockleburs and lovegrass were arranged in bands at varying heights on the dunes, but no pattern was discernible.

The four-tenths inch of drizzly rain the previous night before the visit "froze" the patterns the grass had drawn in the sand as wind tossed the grass leaves about the day before the visit.

Here and there were jackrabbit droppings and a few small black clumps of cryptogamic crusts.

Buena mujer (mentzelia) is a short-lived perennial sometimes found in sanddunes. Their seedpods and stems were still visible, but no new growth had begun.

After studying the tracks for a few minutes, some of the class decided that a fox had leapt at a kangaroo rat near the entrance of his hole. There was no sign that indicated if the fox was successful or not!

Were these two cylindrical sand tubes the work of grassland termites, or water that was dripping from the grass above?

Were these two cylindrical sand tubes the work of grassland termites, or water that was dripping from the grass above?

The cockleburs still had some dead leaves. Cockleburs can grow to over 5 feet tall, but in these dunes, there were none over two feet tall.

This appeared to be the root system of a sunflower, after it had been exposed by the sand blowing away.

Notice how the wind ripples stopped at the edge of a small dune.

It appeared that a ground squirrel had recently emerged from the sand.

A small tumbleweed had turned white after being sandblasted by moving sand.

An unknown plant left this lacy structure after it died.

On top of the highest dune was an old rock corral. Where had the rock come from, and how long had the corral been there. Maybe the Taylors can find out!

The rock of the corral was hardened caliche.

In one small area, hundreds of small winter rosettes of annual wildflowers had germinated.

Pocket gophers had also recently been tunneling in the dunes, leaving the white dry sand on top of the darker moistened sand.

On the hardpan between the dunes, small bone shards were found. Were the bones old or from a more recent kill? They crumbled, so they might have been very old.

Coyote tracks were plentiful on the open sand.

Some of the hardpan areas were extensive.

It was undecided what animal left these tracks. They could have been fox but they seemed small, so they might have been skunk.

Skunks often dig for buried grubs and onion bulbs and other food, so these diggings hinted that the tracks were skunk.

First came the cockleburs, then the dead grass roots that got in the prickles, and that morning came the small droplets of water.

Why had some of the sand held together to form these bizarre shapes?

Was the dark circle a long dead root now decayed?

A coyote circled a clump of cockleburs - did it spray the plants for a scent post, or did it trap a kangaroo rat there?

Dead cocklebur leaves littered the open dunes.

In one place the unusual erosional features extended for a hundred feet.

Burnt rock was common on the hardpan between the dunes. It could have been from Indian campfires long ago, but modern day folks often picnic in the dunes. The group decided that Indians would have reason to bring rocks (to heat water in hide bags - before they had access to metal pots from European settlers.)

Some of the hardpan areas were extensive. These hardpan areas were high above the surrounding farmland, so the hardpan must have formed after the dunes had formed.

Despite the efforts of the local landowners to cover the dunes with the lovegrass, there were still well over a hundred acres of open dunes.

Why were the ripples of the dunes at varying distances from each other?

As of yet, the Sibley Nature Center staff has not identified this plant.

This is the old seedstalk of the above plant - it might be a buckwheat, but the staff is still unsure.

When the class moved to the shinoak covered dunes at the Taylor house, the plant diversity increased tremendously. Spectacle pod dotted the dunes in every direction. Only a few were in bloom.

Penstemon buckleyi seedpod stalks were plentiful in the dunes.

A very cold paper wasp clung to one of the penstemon stalks.

Some of the penstemon had sent up new spring growth, just in time to capture an extra bit of moisture.

Tiny leathery mushrooms were found on dead shinoak branches laying on the ground.

Earth star mushrooms were open because of the rain. When it is dry, they close up. They will disperse their spores over a period of months.

One smooth fungus was purplish in color.

Cory ephedra (endemic to the sandy soils of west Texas) was found on the vegetated dunes.

Packrats built a nest among some of the mesquite growing on the vegetated dunes.

The winter rosettes of wildflowers were sprouting among the leaf litter from the previous year. The white sphere was a mystery.

On the mesquites were three colors of lichen. The sand sage sported new gray leaves.

Canaigre (dock) grows only in loose sand. The large tubers allow it to survive long droughts. It was once used to tan leather.

The group found yet another variety of lichen.

At first examination, it was thought that these were old oyster scale insects, but upon further examination, they might have been a type of fungus, or even a form of gall.

Huge leathery puffballs were plentiful. Some had "exploded" while others retained their spherical shape.

Trompillo fruit were bright yellow on a gray day.

Earth stars set against the fallen shinoak leaves made a beautiful arrangement.Earth stars set against the fallen shinoak leaves made a beautiful arrangement.

Cryptantha minima was one of two species of Cryptantha found. The blooms are about the size of the "o" in the word "about" (or ~1/8" in diameter).

A few puccoon were found. The blossoms are infertile - later in the year blooms that never open self-pollinate. The group discussed why this might be an advantage for the plant - and the theory that grazers might eat the obvious bloom and learn that the plant was not tasty would protect it from later grazing.

Buffalo bur, a close kin to trompillo, produces a seedpod much different than those of trompillo.

A few shinoak acorns were found in the leaf litter.

Underneath a cow patty three exoskeletons of scorpions were found. One species of scorpion specializes in living under dung and feeding on the larvae of the flies and beetles that process the dung.

In one of the blowouts in the vegetated dunes, small clumps of grass with red leaves was found. Despite finding a few seedheads still remaining, the staff of the Sibley Center could not determine the species.

Abronia (sand verbena) grows in loose sand. Later in the year balls of white and pink shoot up from the glossy leaves.

Wolf spider holes were plentiful.

Next to an old shinoak root, tiny bladderpod rosettes struggled.

Underneath another cow patty holes and a tiny larvae was found.

The underside of the cow patty was also riddled with holes.

Bacterial galls were plentiful on the shinoak.

Dripping water had pockmarked the soil under the shinoaks.

Comanche prickly pear was almost invisible in dried grass.

The little "corn on the cob" egg cases were a mystery, while the class was in the field.

An unknown species (to the Sibley staff, that is) of ant was found under another cow patty. A virgin queen was waiting for the right conditions for flight, along with some attendants.

On another Comanche prickly pear, a tiger moth had been impaled. Below the moth was a waxy buildup on the prickly pear - its origins unknown.

The skinny shoot on the left will become a tall partridge pea (with yellow blooms) later in the year. This is the furthest west that Sibley staff has seen the species.

Even sand sage trunks had lichen.

In places, sandsage was dominate. Pocket gopher mounds speckled the area.

This tiny annual chaetopappa (or baby white aster) has only been found in one other dune field by Sibley staff. It was also an isolated dune field, but over 60 miles to the south. A perennial species is common in most habitats of the Llano Estacado.

The red is the new bloom bud of the shin oak, while the leaves are unfurling below.

The large puffballs were often almost buried.

A long-broken box turtle shell was found in the dunes.

Some of the shinoak leaves had bright pink galls on them.

The "corn cob eggs" mentioned above, hatched out tiny Horace's dusky wing butterfly larvae back at Sibley.

The wax on the Comanche prickly pear gave no hint to its origins.

The close up of the tiger moth shows its soft hairy body.

A velvet ant, or cow killer, is actually a female wasp that lays its eggs next to grasshopper eggs, and is a major control of grasshoppers. A number of species are found in west Texas.

An old grass clump had died long ago, and the old crown had turned black.

An older pocket gopher mound had been eroded by rain.

New growth of groundsel was covered with tiny hairs.

New growth of sandsage contrasts pleasingly with its reddish stems.

Was this the leaf arrangement to a plant, or "fasciation" (caused by bacteria.) And what species of plant was it? Sibley staff did not know.

Gnaphalium is a species of daisy without rayflowers. The seedheads are covered with hairs.

Was this an ancient root? It had decayed into a black stringy and moldy material.

Wall flower grows in sanddunes on the Llano Estacado from south of Penwell to at least as far north as Nathan's dunes. Someday Sibley staff will explore the dunes near Muleshoe and see if it can be found there.

A closeup of one of the bacterial galls on the shinoak shows its structure.

Another lichen was found. It is amazing how much a group of people can find when they examine the landscape closely!