Roswell: Highway 285 to Berrendo Road - The Land

 Roswell is situated in the northern region of the Chihuahuan desert. Roswell is on the Great Plains. Roswell is grasslands. Roswell isn't obviously karst but it's karst nevertheless  Roswell is flat but not perfectly so. Roswell is dry but Roswell is an oasis.

Roswell is at 33° 23' 39" N 104° 31' 22" W. Selma, Alabama, where I used to live is at coordinates  32° 24' 59", about one degree latitude difference. So why is the environment so different. Selma is forested..... Roswell is desert. We'll get to that later.

The city is at 3,615 feet altitude. People are surprised by that after seeing how flat it is around here 

The Pecos River flows 7 miles to the east of the city. The highlands that rise to Sierra Blanca begins about 40 miles to the west. The Rockies are about 70 miles to the west. In Denver, I had the requisite photo of the Rockies in my blogs. Here, it will be Sierra Blanco. 

The city has an area of 29.776 square miles (according to the United States Census Bureau). Chaves County, of which Roswell is the largest city, has 6,075 square miles. 

There are actually natural streams in Roswell. Some are dry now because the springs that fed them have been repurposed for industry and agriculture, but Spring River in South Roswell still flows (I think. I haven't made it that far yet.)

The land between Berrendo Road and Pine Lodge is primarily landscaped by Berrendo Creek and the Pecos River.

Pine Lodge from my house

It's flat around here. On my 1.7 mile walk into town, I get an elevation gain of 13 feet (according to measurements made by my AllTrails app.)

There is a blog discussing Berrendo Creek and I'll be posting a blog about Bitter Lakes Wildlife Refuge soon. That park is nestled beneath the Comanche Bluffs in the flood plains of the Pecos River  Berrendo Creek meets the Pecos River a little south of this section.

I say that the land is flat here but there is a little topography 

A draw on highway 285 North truck route north of my house.

Road cut on highway 285

The largest incline I'm aware of is the ravine that Berrendo Creek has cut through town, now dry, something between 20 and 30 feet deep.

Berrendo Creek 

Like the Denver area, the Chihuahuan desert was once an inland sea and many layers of sand, lime, and gypsum have been laid down to make up the rock under my feet. The ground outside looks like ceramic but is actually soft.

Desert soil

It is limestone, or at least dust blown in from limestone. That's evident when it's mixed with vinegar.

If you want to know if a substance contains a carbonate, just add acid. Vinegar is a weak acid but it will make calcite (calcium carbonate) fizz quite nicely, giving off carbon dioxide and leaving calcium acetate behind in solution. Dolomite (magnesium carbonate) may need a little warming to effervesce.

The main bedrocks in the area are limestone and shale but there have been a lot of diverse layers laid down over a long time. My primary source is the strategraphic column provided by the Rockd geology app. (Childs, O.E. (1985) Correlation of strategraphic units of North America, COSUNA.AAPG Bulletin 69:173-180).

The top layer is very recent Ogallala formation deposited by area streams. It's mostly sandstone and gravel. Beneath that is a later of volcanic material from 63 to 19 million years ago. We're just east of the Rio Grande Rift where North America tried to pull itself apart. There has been a lot of recent (geologically speaking) vulcanism in the area. That big mountain on the horizon, Sierra Blanca, is an extinct stratovolcano.

About a thousand meters down is the Grayberg and San Andreas formation limestones overlaid by about 300 meters of impermeable sandstone and shale. The limestone layer is interlaced with cracks that allow storage of a lot of groundwater. The shale cap keeps the water under pressure so that when it finds a channel to the surface it forms the many artesian springs in the area. It also feeds the Roswell water wells.

The Ogallala formation is also an aquifer but, here, it's recharge rate is slow and it can be emptied quickly. Most of Roswell's water comes from the deep aquifer. According to the city website, there are 20 deep wells that draw water up, chlorinates it, and distributes it out to the city. 

Roswell takes samples of treated wastewater daily, 60 samples a month, to test for bacterial contaminants and tests drinking water quarterly for chemical contaminants.

I bought a test kit (H2O OK Plus) to check our tap water. Most of the tests are on three test strips although the coliform test requires a tube of water plus reagent to sit a while.

The tests were easy and I was very happy with the results  

The water is hard but 247 parts per million is far below EPA requirements.

Hard water is water with high mineral content, usually calcium and magnesium carbonates. It happens when water is stored in a limestone or gypsum aquifer. Roswell's aquifer is mostly limestone but there is still plenty of gypsum and even some interesting evaporates.....minerals that form when landlocked lakes evaporate. They're touchy for mineral collectors because they tend to draw humidity out of the air and then dissolve in it.

Hard water might have some health benefits (except for kidney stones for people predisposed to it) but it can play havoc with pipes and laundry. Calcium carbonate tends to precipitate out in cakes. Also, the calcium ions will combine with the sodium stearate (soap) to firm an insoluble, slimy, scummy precipitate of calcium stearate. The best way to tell if the water from your tap is too hard is that you can't get soap to lather. We get scum but the soap will lather. And unlike some folks, I like the mouth feel of coffee creamer in hard water 

Roswell gets it's water from the deep aquifer but there are three major streams and a few intermittent tributaries that run through town. I explore Berrendo Creek in an earlier blog. Most of its length is usually dry but when it's wet, there's a flood.

I haven't seen the other two yet.....they are Spring River and Hondo Rio. All of these streams are tributaries of the Pacos River that flows 7 miles east of Main Street  I'll talk about the others when I get to explore them.

The Pacos River at Bitter Lakes 

Most of the natural water here is green. The green isn't pollution..... it's calcium. Here's another calcium loaded stream in Alabama 

Brushy Lake, Northwestern Alabama

The climate here is hot and dry with occasional cold (night and winter) and rare rain, which is sometimes devastatingly torrential.

My family moved down from Denver late in October of last year (2025). The days were warm and cool. It was a good time to move into the desert. The nights, as is normal year round, was cool. By December, the days were cooling down. The vegetation which plagued me on my trips to town for supplies was dying down to stubble. We had some cold days and one snow between January and March. I think it has rained three times since we moved, never hard. Wet ground evaporates quickly. The sunsets are always gorgeous given the capacity for the dry air to hold dust suspended and the frequent hard winds that whip it up. The skies are vast and blue.

The following is from the Wikipedia article about Roswell.

We have a cool, semi arid climate and four distinct seasons. Winter is cool and there is occasional snow that doesn't hang around long. Spring oscillates between warm and cool but there can be cold snaps.  There can be fierce winds. I clocked one gust last week at around 40 mph. I had to fight to walk against it. Summer is hot. Roswell experiences around 30 days out of the year above100° F. The North American monsoon season occurs during the summer and can bring torrential downpours and disastrous flash floods. The three streams that run through town can become raging rivers. The Berrendo ravine can fill up quickly.  Autumn brings relief. Things cool off although there can still be hot days, and snow is possible from October to March 

Since humidity is generally low and humidity causes changes to be more gradual, shade is considerably cooler than sun.

The record low: -24° F. (January 11, 1962, February 8, 1933)

The record high: 114°F. (June 27, 1994)

But the ground is that pretty cream color with glossy ground cover.....high albedo! This is a solar furnace. Hot anywhere else is HOT here.

So, the weather report for today (I'm taking a day off!):

Air Quality Index is fair at 45

No precipitation expected

Wind at 5.9 miles per hour from the west (prevailing winds here are mild breezes from the mountains (west) and brutal winds from the south in the leading edges of fronts and from the north after the front passes - beware the tumbleweeds. They're cute but vicious!

Ultraviolet index is high ( as usual, at altitude, there isn't a lot of filtering from the atmosphere)

Humidity is 17%

Barometric pressure is 30.17 inches of mercury. (About 1.02 bar, practically sea level.)

Why is Roswell so different from Selma? 

The strip of land bordering the Rocky Mountains to the east used to be a vast, shallow inland sea. Over millions of years, plankton died, sank to the bottom, and left a thick layer (several thick layers, actually, interspersed with mud) of their calcium carbonate skeletons and shells. That turned into limestone....highly reflective limestone that baked and efficiently reflected heat back up into the air when the sea dried up 

But more importantly, New Mexico is in the rain shadow of the Rocky Mountains. As humid air flows in from the Pacific Ocean, it rises up over the Cascades and the Sierra Nevada mountains and the Rockies into cooler heights where most of the humidity precipitates out. This is the air that Montana, Wyoming, Colorado, New Mexico, and Mexico gets. The eastern United States gets humidity pumped in constantly from the Atlantic and the Gulf of Mexico. It's dry and there's nothing to buffer the heat 

So my journey to adapt to desert life continues. This Arctic wolf is going to have fun. It's not like I can lock myself in an air conditioned house and never come out. My heart condition requires real activity.

Well, adventure might be painful, but it's fun. No pain.....no gain!

:)

So.....land, air, and water. It's where you live. How is your world? What kind of rock is under your feet? Is there plentiful water or is it dry? Are there caves near you? That's a part of karst geology. Do you have seasons or is it summer one day and.....suddenly winter! Have you tested the water from your tap? Water testing kits are easy to come by, usually from local hardware or home supply stores.

What causes the color? Chemical change!

High Falls, Alabama

Red Rocks, Colorado

Red Rocks, Colorado

Flooded creek in Alabama

Noccalula Falls, Alabama

Red Rocks in Colorado and red dirt in Georgia are red for the same reason...iron.

Iron is one of the most common elements on Earth. Nobody's been to the Earth's core but everything we know about it tells us that it's a little less than 90% iron (about 10% is nickel with about 3% lighter elements like silicon, sulfur, and oxygen.) We figure that because our calculations for the density of the Earth from how it orbits the sun, it's magnetism, and the way shock waves pass through the core, and everything else points to iron.

And the crust is full of iron oxides...rust. you won't find much pure iron. If you do, it's probably a meteorite. Metallic iron rusts in short order in the oxygen atmosphere of Earth.

Why is iron so common on Earth? The planet is composed of the dust that came together to make up the whole solar system. The dust came from stars that had lived, grown old, and died before our Sun. Stars create energy by combining light atoms, under incredible pressures to form heavier atoms (It's called "fusion".) Once you get the reaction going (gravity packs the materials together under great pressures and temperatures), it will just keep going. The products are heavier atoms and energy. Chemists call such reactions that give off energy, "exothermic reactions".

First, hydrogen atoms are packed together to form helium, then carbon is formed, then silicon, and finally, iron. Why "finally"? Well, it turns out that iron is the heaviest element that can form in an exothermic fusion reaction. All the heavier elements have to have energy put into the reactions to keep them going. Elements like gold and uranium are created in exploding stars...novas and supernovas... there's plenty of extra energy there!

So, the commonest elements on Earth are also the commonest elements in stars. Hydrogen is common in our water, and there's plenty of oxygen, carbon, and silicon along with the iron.

But what about the helium? The only reason hydrogen is so common is that it's bound up in the heavier compound water, otherwise, gravity wouldn't be able to hold such a light substance to the Earth. It would have all leaked out into space long ago. Helium, though, doesn't bond very easily with other elements so...away it goes.

Iron, though, is a very reactive element and it does like to bind with other elements and one of the most available elements for it to bind with is oxygen. We know iron oxide by it's common name...rust.

Want to see rust in action?

Get two iron or steel nails (not chrome plated or stainless steel. If you buy nails for this demonstration, find a package that warns not to use them if surface rust will be a problem.) And place them in test tubes. Mark one test tube "Dry" and stopper it. Mark the other "Wet", push a wad of damp cotton ball in after the nail and stopper it. Let them sit for a couple of weeks or longer.

Nails before demonstration

Nails after exposure to air. The right one was in the wet test tube.

The nail from the dry tube magnified

The nail from the wet tube magnified

Iron oxide is iron and oxygen, and both nails were exposed to oxygen, so why did the damp nail rust and the dry one didn't?

Actually, the dry nail did rust, but it rusted so slowly that I couldn't tell. Over years, I would have been able to see the rust. In a humid environment, water takes part in the reaction to speed the rusting up. If there is salt in the water, it really speeds things up. That's why things rust much faster in Florida than in Alabama, and things rust faster in Alabama than in Arizona.

Rusting is a chemical reaction because the product of the reaction, iron oxide, is a different substance than the reactants, iron and oxygen.

Iron is a transition element. It can have several charged states and that means that it can combine with oxygen in different proportions to form different oxides. Most of the colors in rocks are from these different oxides of iron. Here are two of them.

The white plates above the rocks are called "streak plates". They're made of unglazed porcelain. You can rub a mineral across them to see what their powder looks like. Powder color is more reliable for identification than the color of a chunk of a mineral. The mineral to the right, hematite, can be red, black or brown, but it's streak is always red. In it, two atoms of iron combine with three atoms of oxygen. Hematite is what makes Red Rocks red.

The other mineral in the photograph is magnetite. It has three atoms of iron to four atoms of oxygen and it's streak is always black. It's also attracted to magnets and might even be magnetic. The ancients knew magnetite as "lodestone" and they magnetized other iron items, like compass needles by rubbing them against these natural magnets.

Another common iron oxide includes water in various amounts in its makeup. Because it has a yellow streak, it's called "limonite". It's what colors the ground at Englewood Reservoir.

These iron oxides are pretty but they're also important for another reason. They're the primary iron ores.

Iron has another charged stated that is green and most of the green stones in nature are also colored by iron. A few common green iron bearing minerals are olivine, amphibole, epidote, and serpentine.

In physical changes, no new substance is created. Here is some magnified sea salt.

It's a pretty, clear, blocky crystalline substance. When I dissolved it in water and let the water evaporate, I got this...

This physical reaction is arguably as important as the chemical reaction that produces rust. Rain dissolves salts from rocks and washes them into streams. The streams run into oceans and landlocked lakes like the Dead Sea between Israel and Jordan, the Salt Lake in Utah, and the Salton Sea in California. The water evaporates and the water gets salty. That's why the ocean is salty and that's how salt deposits form that can be mined for table salt.

It's not always easy to tell if a change is chemical or physical but if you pay attention, you can develop a feeling for it. The biggest difference is that chemical changes give you different substances than what you started with; physical changes don't. Ice and liquid water may look different but they're both water. When ice melts, you get your water back.

The next time you go on a hike, appreciate iron for most of the colorful rocks around you.