#84 - Saline Seep makes Soil Too Salty for Crops

Photo courtesy of Montana Salinity Control Association

Too salty . . .
This aerial photo was taken over Interstate Highway #15 near Power, Montana (25 miles northwest of Great Falls). The white patches to the right of the highway are areas where the soil has been damaged by saline seep, a problem that has ruined more than 300,000 acres of farmland in Montana. The word "saline" refers to the salts (mostly sodium and magnesium sulfate salts) that build up at the surface, making it difficult for crops to grow there.

In a nutshell . . .
The diagram below illustrates how saline seep typically occurs. Water soaks into the ground at the "recharge area". Excess water that is not absorbed by plants moves (percolates) downward through the soil. On its way it dissolves (leaches) mineral salts. In the diagram, the salt-laden groundwater reaches an impermeable layer and then migrates to a lower area where the water table is at the surface. At this "discharge area", the water evaporates, leaving the salts behind as a white crust on the surface.

"Summer Fallow" is the culprit . . .
Although sodium and magnesium sulfates (salts) occur naturally, saline seep is usually not natural occurrence. In Montana the problem is often related to a "crop-fallow" system of farming. With this type of farming, every other year a strip of land is kept barren of vegetation by plowing and/or using herbicides in order to allow soil moisture to build up and eliminate weeds. On these strips, called "summer fallow", there are no plants to absorb the water from rain or melted snow, so it more easily soaks through the soil, leaching salts along the way and causing an elevated water table.

Term: leachate

#85 - Blocking High Forced Storms Away From Montana

High means dry. . .
Montana experienced an unseasonably warm, dry February in 2005 as a result of an area of high pressure that parked itself over the northwestern USA for much of the month. Areas of high pressure, sometimes called "high pressure systems", or just "highs", are places where air is sinking. As it sinks, the air is compressed and warmed, making high pressure days more likely to be clear with sunny days, cold nights, and very little precipitation. Weather systems generally move across Montana from west to east, typically passing through over a period of a few days. But the high of February 2005 stayed put for weeks, causing the jet stream and the storms that it guides go around Montana. High pressure sytems that do this are sometimes referred to as "blocking highs".

Back in the groove . . .
Finally in March the high dissipated and storms began to move across Montana once again, bringing much needed moisture to the state. The image above shows two major storms, one that affected the eastern USA and the another that brought significant snow to our state. Both storms were mid-latitude cyclones, usually just called "low pressure systems" (or "lows"). In disturbances such as these, air flows counterclockwise, rising as it spirals toward the center (L on image below). Whenever air rises, it cools by expansion, helping clouds (and precipitation) to form. Low pressure systems usually feature a fairly distinct cold front (blue, spiked line) where cold air is pushing into warmer air, and a less distinct warm front (red, bumped line) where warmer air is pushing into and over colder air. Both warm and cold fronts force the warmer air to rise and cool by expansion, helping clouds to form. Quite often the clouds in a low pressure system form a comma shape, especially in the eastern USA where there is more humidity (Gulf moisture) and no tall mountains to disrupt the motion of air within the system.

Watch The Ultimate Cloud Demonstration (3.5-minute video) to see the relationship between pressure and clouds.

Eyes in the sky . . .
Both images on this page were taken by N.O.A.A.'s GOES-East, a geostationary satellite that provides a view of the lower 48 states and the western part of the Atlantic Ocean. The GOES-West allows meteorologists to monitor storms over the Pacific as they approach the USA. Both satellites can produce three types of images, including infrared, water vapor, and visible. Infrared images, like the one at the top of this page, are important because they show where the coldest cloud tops are, the ones most likely to be causing precipitation. Also, infrared images do not depend on daylight as visible images do. At the time the above image was made it was snowing in Montana and there was significant rain and some areas of severe weather (red) in the east.

Below: This "visible" image shows where there were clouds as the two storms made their way across the country. I estimated the location of the fronts and the direction of the winds (green arrows), and then added them to the image.

Just thought you'd like to know . . .
N.O.A.A. stands for National Oceanic and Atmospheric Administration. G.O.E.S. stands for Geostationary Operational Environmental Satellite.

Term: geostationary

#82 - The Arrival of Captain Lewis at the Great Falls of the Missouri, June 13, 1805

Painting by Charles Fritz, Oil on Canvas 42" x 65"

An agreeable sound . . . On the morning of June 11, 1805 Captain Lewis and four men set out from a fork in the Missouri River (now referred to as “Decision Point”) near Loma, Montana in search of “the great waterfalls” that the Indians told them to expect. Clark stayed with the main party and attended to Sacagawea who was ill. The significance of finding the falls is that it confirmed that they had taken the correct fork in the river. Fritz’s painting shows Captain Lewis as he first gazed upon what we now call “The Great Falls” on June 13, 2005. Lewis wrote about the discovery in his journal:

I had proceed on this course about two miles with Goodrich at some distance behind me whin my ears were saluted with the agreeable sound of a fall of water and advancing a little further I saw the spray arrise above the plain like a collumn of smoke which soon began to make a roaring too tremendious to be mistaken for any cause short of the great falls of the Missouri. Here I arrived about 12 Oclock. From the reflection of the sun on the sprey or mist which arrises from these falls is a beautifull rainbow produced which adds not a little to the beauty of this majestically grand senery. (Lewis didn’t have spell-check on his laptop.)

A set of five . . .
The Great Falls (shown in the painting) were actually the first of five waterfalls encountered by the explorers as they journeyed through an 18-mile stretch that included the area now occupied by the city of Great Falls. Although each of the waterfalls has its own name (Great Falls, Crooked Falls, Rainbow Falls, Colter Falls, Black Eagle Falls) the set of five waterfalls is referred to as “the Great Falls of the Missouri.”

Geology caused the falls . . .
Each of the falls is caused by the presence of an especially tough layer of sandstone unit in the Cretaceous Kootenai Formation. A “formation” is a large area where a particular type of sediment was deposited. The Kootenai Formation consists of sedimentary rocks formed from sands and silts that accumulated in a shallow lake, or as rivers emptied into a marine embayment roughly 115 million years ago. The formation includes alternating layers of siltstone (shale) and sandstone. The city of Great Falls is built on the crest of a gentle fold known as the Sweetgrass Arch. As the arch has been worn down, the sandstone has been more resistant to weathering and erosion, causing the formation of the set of waterfalls that drop the Missouri River more than 500 feet over 18 miles.

Above right: This aerial photo, provided by Jim Wark of Airphoto - North America, shows the same falls featured in the painting. Ryan Dam, which can be seen just above the waterfalls, is one of five hydroelectric dams that have been built along the Great Falls of the Missouri. Ryan Dam is about 8 miles northeast of the city of Great Falls.

A month of hard work . . .
The waterfalls on the Missouri River proved to be a huge obstacle for the Corp of Discovery. It took the expedition a month to move everything upstream above the last falls – just 18 miles away. This portion of the journey is known as “The Portage.”

Term: portage

#83 - Grasshopper Glacier North of Yellowstone Park

Photo courtesy of Alexandre Lussier, Dept. of Physics, Montana State University

One of the most unusual "Earth Science places" in Montana is Grasshopper Glacier located 70 miles southwest of Billings (10 miles north of Cooke City). The Glacier, which sits at 11,000 feet in the heart of the Beartooth Mountains, takes its name from the millions of grasshoppers embedded in it. Entomologists identified the hopper as a species of migratory locusts (Melanoplus spretus) commonly called "Rocky Mountain Locusts".

Migration gone bad . . .
Centuries ago this species of locust was found in large numbers throughout the West. Scientists believe they became embedded in the ice when migrating swarms, passing over the high mountains, became chilled or were caught in a severe storm and were deposited on the glacier. As snow built up over decades, the grasshoppers were buried deeper and deeper. Then as the climate in the area has warmed over recent centuries, melting of the snow exposed the embedded grasshoppers, and they were discovered. Until recent years, visitors could dig perfectly preserved specimens from the ice. However, years of light snow during the winter and thawing during the summer months have exposed many of the grasshoppers to decomposition.

University of Wyoming study . . .
Fortunately there are other glaciers in the Rockies that also contain swarms of grasshoppers, and in the 1990s a team led by Jeffrey Lockwood, Professor of Entomology at the University of Wyoming, found one in Wyoming that contained intact grasshoppers. The team used radiocarbon dating to determine that the swarm was blown into the mountains in the early 1600s.

Glacier, or Snowfield? . . .
In order for a glacier to form there needs to be build-up of snow over many years. At lower elevations where most of us live, all of the snow that falls in the winter melts in the spring. At high altitudes that isn't always the case. For example, an average of 8 feet of snow might fall every winter, but only 3 feet melt away every summer, leaving a build-up of 5 feet of snow. When this goes on for decades these annual 5-foot layers form, one on top of the other, and begin to compress the layers beneath. As a result the snow nearer the bottom is changed into ice, and a glacier is born. Apparently not everyone is convinced that has happened with Grasshopper Glacier. Not enough snow built up to transform the bottom layers into ice, so technically Grasshopper Glacier is simply a "snowfield" that has been around for a very long time. But don't expect a name change anytime soon . . . "Grasshopper Glacier" has a much nicer ring to it than "Grasshopper Snowfield" does.

NOTE: In 2000, Grasshopper Glacier was approximately 1 mile long and 1/2 mile wide. Scientists believe it was over 4 miles long at its peak during colder times.

Below: Robert Grebe took this photo of Grasshopper Glacier in September of 2010.

Term: entomology

#86 - Lime Kilns outside of Helena

Photo by Keith Benson

Not that kind of lime . . .
When you hear the word "lime" you probably think of the green citrus fruit used to give 7-Up its distinct flavor. This photo, which was taken less than half a mile south of Helena, shows the ruins of kilns (ovens) that produced a totally different type of "lime". The type of lime produced here, calcium oxide (CaO), was used to make mortar that was needed to construct buildings of brick and stone in Helena during the late 1800s and early 1900s.

A little chemistry . . .
The kilns were built here because of the availability of the light-colored limestone, which can be seen on the slope behind the kilns. Limestone is a sedimentary rock primarily made up of calcite (calcium carbonate: CaCO3). Workers blasted or quarried the limestone and then hauled or rolled the rocks down the slope, dumping them into the tops of the kilns. Pine fires in the furnace beneath the kilns burned constantly changing the calcite into lime.

500 to 600 C CaCO₃ (s) -----> CaO (s) + CO₂ (g)

After several days the powdered lime was shoveled into cooling sheds adjacent to the kilns. Once cooled, it was hauled to building sites around Helena, where it was mixed with sand and water to make mortar. Each kiln could produce about 20 tons of lime every eight hours.

A little history . . .
Irish-born James McKelvey leased and then owned the kilns, supplying the mortar used to build the State Capitol. Lack of railroad access eventually forced closure of the kilns around 1910. The blocks of sandstone used to make the Capitol came from a quarry near Columbus, Montana.

Mortar: a thick mud-like mixture of lime, sand, and water used to hold bricks or stones together as buildings are constructed

Cement: a powdery mixture that includes mostly lime, as well as other materials such as clay, gypsum, etc.

Concrete: mixture of cement, gravel (pebbles), water

Term: quarry

#87 - Montana's Famous "Mummified" Dinosaur

"The best-preserved dinosaur remains in the world belong to Leonardo, a 77 million year old Brachylophosaurus. Around 90% of the body is covered with fossilized soft tissue." (Guinness World Records L.T.D.)

Leonardo was about 23 feet long when it died, and 4-6 years old.

A treasure is discovered . . .
Leonardo was discovered near Malta, Montana on July 27, 2000 when Dan Stephenson of Minot, North Dakota noticed the exposed mid-section of Leonardo’s tail and part of its pelvis in a large channel sandstone deposit within the Judith River Formation. This particular formation is made up of sediments (mud, sand) that were deposited during the late Cretaceous Period when the environment in eastern Montana was similar to that found today in the Mississippi Delta region.

More than just bones . . .
This photo, taken in Malta, Montana, shows Leonardo along with paleontologist Nate Murphy, head of the Judith River Dinosaur Institute. What’s sets Leonardo apart from other dinosaur fossils is that 90 % of his skeleton is covered with (fossilized) tissue, including skin, scales, muscle, foot pads . . . Even his last meals, which included ferns, conifers, and magnolias, were fossilized in his stomach. Minerals have replaced the soft tissue and stomach contents just as they do when wood becomes “petrified”. In addition to being a 77 million year-old “mummy” that will keep scientists busy for years, Leonardo was one of only four brachylophosaurus* specimens that had been uncovered, and he was the first fully articulated sub-adult ever found. Leonardo is believed to have been 3 or 4 years old when he died.

Nature’s takes it course . . .
When an animal dies, decay bacteria move in to begin consuming the soft tissue. Scavengers show up to nibble on the flesh and flies stop by to lays eggs in the carcass. As maggots hatch from these eggs they help consume the rotting flesh. Usually within a matter of weeks or months most of the soft stuff has decomposed. The bones, which may take years to be weathered away, often become scattered by wind, water, or scavengers.

Rare circumstances . . .
If a dinosaur died in just the right place, possibly along a river or on a delta, it might have become buried by sediment. If this happened soon after the animal died its body would have been somewhat protected from the elements, and it might have become fossilized. However, it is even more unusual to find a dinosaur fossil that includes anything but bones, indicating that burial rarely happened before the soft tissue rotted away. In fact, Leonardo is one of only four dinosaur fossils ever found to be classified as a "mummy" because of the amount of soft tissue that was preserved. Unfortunately, the other three were uncovered in the early 1900s, when excavation and preservation techniques were not as advanced as they are today.

*Brachylophosaurus: a species of duck-billed dinosaur

Terms: petrify, delta (of a river)

Update: Currently (2025) Leonardo is currently on loan from the Great Plains Dinosaur Museum in Malta, Montana, and is on display at the Fukui Prefectural Dinosaur Museum in Japan.

#88 - Nuclear Bombs and Thyroid Cancer: The Milk Connection

Map courtesy of the National Cancer Institute

From 1951 to 1958 the U.S. government conducted 90 above-ground nuclear bomb tests in the desert northwest of Las Vegas, Nevada, sending particles contaminated with radioactive iodine-131 (fallout) across much of the country. According to a 1997 report from the National Cancer Institute, the county with the highest per capita dose of radioactive Iodine 131 from the bomb tests was Montana's Meagher County located between Bozeman and Great Falls (White Sulphur Springs area). Furthermore 15 of the 25 counties with the highest doses of Iodine-131 are in Montana. Those "hot spots" are the brightly-shaded counties on the map shown above. The distribution of fallout from each of the bomb tests was dependent on the strength and direction of winds, especially the jet stream, at the time of the explosion.

Casualties of the Cold War . . .
Iodine-131 is a radioactive isotope that decays rapidly in the environment. In fact its radioactivity is reduced by half every eight days (half-life), so it is only dangerous for about two months. But if it is ingested before it breaks down, it concentrates in the thyroid gland, which is made up of the only cells in the body able to absorb iodine. There the I-131 can cause thyroid cancer, which may not appear for several decades. The National Cancer Institute estimates that exposure to fallout from the bomb tests could produce over 200,000 excess cases of thyroid cancer.

Got milk? . . .
The primary way that people were exposed to I-131 was by drinking contaminated milk. The radioactive iodine was carried over Montana as part of the fallout, and fell on pastures where it was eaten by cows, contaminating their milk. Smaller amounts contaminated other dairy products and leafy vegetables. Children of that era (1950s) are at higher risk for a couple reasons.

1. Children generally drink more milk than adults.

2. Children have smaller thyroids.

Therefore, with children, more radioactive Iodine-131 would have built up in a smaller amount of tissue. Furthermore if children in areas such as Meagher County consumed fresh milk directly from the cow, their exposure to radiation would have been even greater. Fresh milk from backyard or farm cows usually contained more I-131 than store-bought milk because processing and shipping milk allowed more time for the radioactive iodine to break down.

Montanans excluded . . .
In a report by the National Cancer Institute, released in 1997, it was determined that ninety atmospheric tests at the Nevada Test Site deposited high levels of radioactive iodine-131 across a large portion of the United States, especially in the years 1952, 1953, 1955, and 1957 . . . doses large enough to cause anywhere from 10,000 to 75,000 cases of thyroid cancer. The Radiation Exposure Compensation Act of 1990 allowed for people living downwind of test site for at least two years in particular Nevada, Arizona or Utah counties, between 21 January 1951 and 31 October 1958, or 30 June and 31 July 1962, AND suffering from certain cancers or other serious illnesses deemed to have been caused by fallout exposure to receive compensation of $50,000. By January 2006, over 10,500 claims had been approved, and around 3,000 denied, for a total amount of over $525 million in compensation dispensed to "downwinders". Unfortunately, victims who were living in Montana counties at the time of the tests were not included in the program.

A little good news . . .
Thyroid cancer is a very slow growing cancer and accounts for only 1 percent of all cancers in the United States. An estimated 16,100 cases will be diagnosed this year with 1,230 being fatal. It is a highly curable cancer with the five-year survival rate at 95 percent.

Terms: isotope, half-life