Now, here’s what the experiment looked like on Friday, December 4th, after the air temperature went below freezing, hitting 24 degrees Fahrenheit overnight:
Three of the jars had frozen water in them, including the jar with SALTY water. No one predicted that! The two jars that did not freeze were both sealed tight — there were no holes in their lids.
Here’s a closer look at Jar A, which started out as cold, fresh tap water, and was covered by a plastic lid with holes drilled in it:
Jar B showed a similar pattern, although the sheets of ice were more horizontal than vertical:
Jar D was most surprising. I was expecting the salty water wouldn’t freeze, but the top part of the jar was frozen fairly solid. However, the bottom of the jar was not frozen, but had a bunch of bubbles sticking to the side of the jar:
So, that leaves us with two mysteries to solve:
Why did most of the water in the salty jar freeze?
Why did the water in the sealed jars not freeze?
I have some ideas, but I won’t tell you about them yet. However, I will give you one hint about the second mystery. Here’s what the lower part of salty Jar D looked like on December 2, 2009 — three days after the experiment started, but before the temperature dropped below freezing:
Feel free to tell us your ideas in the comments section (below) or on Facebook.
According to the closest Oak Park weather station, the temperature hovered just above freezing early this morning. But skies were clear, so heat radiated from the upper layers of our backyard pools. By dawn we had our first backyard ice of the fall:
If it had been cloudy, or if there had been a breeze to circulate the water in the pool, we wouldn’t have had ice. But with a clear sky and calm air, we got these fantastic ice patterns right outside our back door!
Why the triangles in the ice? I’m not sure, but that’s the pattern we got last year in similar situations. If you look at this blog post from last February, you’ll see another example of triangular-patterned ice. That post talks about “wrinkles” forming in the super thin ice — maybe triangles develop where three wrinkles intersect. Anyway, that’s a puzzle for me to work on over the next few months.
There’s no natural water where kids can go and play, except after big storms and snow melts, and they set things up so even that’s supposed to drain away. There are no streams, no lakes closer than Columbus Park — just some human-made garden ponds in fenced off yards. And the Park District swimming pool. And the drainage ditches along the highway, which have cattails and Red-winged Blackbirds and mosquitos, but those are also fenced off too. But there’s no stream or pond or swamp where I can let the boys wade free, throwing rocks, racing sticks, collecting frogs and eels.There’s no place like I had growing up.So, we import our water through pipes, then fill containers in our back yard. There’s a plastic swimming pool where our pet turtles swim in summer; another half sand, half water, with a pump to make a stream; a pool with buggy water from the golf course pond behind Grandma’s condo; a black container for panning gold; and a pool that’s just for playing.
Every fall I promise to drain the pools and store them, but it never happens. Then I wake up on a winter morning and find this
Hackberries are one of my favorite street-side trees. Their warty bark is entertaining year ’round, and I always enjoy the assortment of galls and growths found on their leaves and twigs. (I blogged about Hackberry Nipple Galls here.) On yesterday’s walk through south Oak Park, I noticed that Hackberry fruits are ripening on a few neighborhood trees:
Only a few fruits on this tree were ripe, but there were many raisiny purple Hackberry fruits on the sidewalk (perhaps knocked there by recent storms).
If you bite gently on a ripe Hackberry fruit, you’ll often taste a bit of sweetness (which varies tree to tree). That’s why some folks call these “Sugarberry” trees. Just don’t bite too hard! Inside the thin fruity coating is a seed that’s hard as rock. The seed actually contains a bit of calcium carbonate, which makes up limestone rock. That’s one reason Hackberry seeds are readily preserved in soils. I’ve even found 40-million-year-old Hackberry seeds buried in ancient soils in the Badlands of South Dakota and Nebraska (see examples here).
Like me, many birds eat Hackberry seeds in south Oak Park, including Robins, Cedar Waxwings, and Starlings. Last fall I watched a flock of Crows feeding in a Hackberry tree along Oak Park Avenue near Lincoln School.
Galls, fruits, fossils, and birds — no wonder I love Hackberries!
Here are links more information about Hackberries:
The Collector’s Garden is a special rock garden where children can pick the rocks and shells (instead of picking flowers). It’s on our front lawn in south Oak Park:
If you visit the Garden, please follow the rules:
We stock the Garden with dozens of kinds of rocks and shells, plus shark teeth and other fossils:
Please be careful — the shark teeth are still very sharp! And please excuse the dead leaves left from last fall. The worms and bugs will eat them up over the next month or so. (Or maybe you didn’t want to think about that.)
Here are some resources to help you identify the rocks you find:
Where do we get these specimens? Many types of rocks are sold in 50-pound bags at hardware or garden stores. We buy some shells and fossils in bulk at the local rock club shows or various Web stores. We find other things on trips, or folks give them to us. We’re just always on the look out. Here’s a Web page with information about some of the specimens you may find in the Garden, including where you can get them: http://www.saltthesandbox.org/wonderworks/saltedsandbox.htm
Why do we do it? Because we’re trying to make our densely populated neighborhood a better place for nature-loving kids. When my boys were little, I used to feed their collecting interests by “salting” their sandbox with small specimens of natural things. Now we salt our gravelly garden for the whole neighborhood.
By the way, if you don’t know where we live but want to visit, please e-mail me at firstname.lastname@example.org.
Neighborhood Nature will bring hands-on science and nature activities to three events during March and April:
ESCONI Gem, Mineral, and Fossil Show: THIS WEEKEND, Saturday and Sunday, March 14 and 15, 2009. ESCONI is the Earth Science Club of Northern Illinois, and our annual show brings exhibitors and dealers from around the Midwest to the College of DuPage for two days. Gail’s favorite jewelry maker (Exclusive Inspiration) will be there, along with her Dad, who is Ethan’s favorite fossil dealer (Rib River Fossils). Our family will help run the ESCONI Juniors Kids’ Corner activities both days. We’ll have free collecting and craft activities for children and a sales area with inexpensive rocks, minerals, and fossils for sale just to children and teachers. Web address: http://www.esconi.org/esconi_earth_science_club/esconi-gem-mineral-show/
Earth Day at Wonder Works, Wednesday morning, April 22, 2009. We’ve done informal hands-on activities at Wonder Works since it first opened in north Oak Park. Our 2009 Earth Day activities are currently being designed to illustrate a range of ways that adults can nurture young children’s love for the natural world, even if they live in a densely populated place like south Oak Park. (That’s been the story of my life for the past dozen years!) Many of the activities will be based on David Sobel’s design principles for helping children make connections with nature, but I’ll give them an urban spin. There are two basic ideas: (1) Adults should help children learn to love the natural world before they asking them to save it, and (2) children learn that love by play and exploration in natual settings. As summarized on a series of blog postings by a children’s garden educator, the ways children learn to love nature include: Adventure; Fantasy and Imagination; Animal Allies; Maps and Paths; Special Places; Small Worlds; and Hunting and Gathering. We’ll provide details about our Earth Day activities as we invent them during the weeks before the program.
Academic Fair at Washington Irving School in Oak Park, evening of Wednesday, April 22, 2009. We’ll run informal activites in the Mini-Gym while the main event — the student projects — are on display in the Main Gym. We’ll probably bring a combination of ESCONI and Earth Day activites, with some technology and physical science activities as well. (If Irving School families want us to bring back favorites from the past, please let us know as soon as possible.)
While living a life consumed with raising boys and exploring living things for this blog, part of me is always thinking of the past. Sure, I think about my childhood and how it compares with the ones my boys are living. I also think about folks who built and visited Columbus Park a century ago. Heavy rains bring ancient lakes and beach ridges to mind. But some things take me even further back, like a certain gray stone found in many buildings in the Park:
Looking closely at the blocks of limestone, there are fossils — evidence of ancient life and clues to the origin of this stone:
The rock is limestone, made of tiny bits of broken fossil hashed together and then cemented with a mineral called calcite. Because the fossils, like corals and brachiopods, are only found in sea water, this rock must have formed on the bottom of an ancient sea. Because these particular fossils match extinct species that lived about 350 million years ago, we know that’s when this limestone formed.
This limestone has other uses in the Park. On the covered terrace of the Refectory, limestone has been carved into urns and made into steps and building decorations:
A closer look at this limestone reveals another common fossil from the ancient sea:
For the collectors in our family, finding fossils can be frustrating when we can’t take them home. So Dad’s found other ways to let kids collect fossils from the Indiana Limestone. Over years of collecting in southern Indiana, he’s scraped up several gallons of rusty-red soil from hilltops formed on Indiana Limestone. The dirt is filled with tiny fossils dissolved out of the rock over thousands of years (by rain less acid than what humans make today). Go here to see close-up views of the fossils we find.
It was 19 degrees Fahrenheit and windy on this morning’s walk through Columbus Park. Despite the wind chill, I enjoyed both the patterns in the ice and the scores of Robins feeding on the golf course.
The most interesting ice formed at the edges of golf course puddles:
I saw at least 80 Robins, almost three times what we saw on Sunday.
Most Robins fed on the golf course, on the east sides of wooded areas. There the early morning sun warmed them while trees sheltered them from cold west winds.
Tuesday’s warm front brought the Robins to the Park and filled the puddles. As usual, a cold front followed — its bitter winds froze the puddles and the soil. If the Robins can’t find worms, they’ll probably switch to fruit, their winter food. That’s why we put out raisins for our backyard Robins.
To read about whether Robins are a reliable sign of spring, go to this page.
Nature Note added at 6:15 p.m. the same day: Late this afternoon I watched as our backyard Robin pulled a huge nightcrawler from the soil below the thistle feeders. It was so big he had trouble eating it. I guess I won’t have to worry about that Robin, despite the freezing temperatures.
Nature Note added at 6:50 a.m. the next day: It was 16 degrees this morning. When I saw a Robin in a tree near our yard, I did worry. So I put out more raisins.
Nature Note added on March 28 (more than 2 weeks later): This past week there have been even more Robins in the neighborhood. On Friday, March 27, I found at least 200 Robins in Columbus Park, mostly on the golf course. On Tuesday, March 25, I counted 136 Robins on a 2.5 mile walk through south Oak Park.
Our neighborhood was once the bottom of a lake. That lake shrunk in size to become Lake Michigan, but ten thousand years ago the larger version covered most of Chicago and Oak Park. That prehistoric lake is known as “Lake Chicago.”
When rains are long and hard, the ghost of Lake Chicago tries to make a comeback. Storm sewers usually rescue residential areas from its return. But, after three and a half inches of rain over the past weekend, Lake Chicago has returned to Columbus Park:
Visiting the flooded Park as the storm subsided, the boys and I checked every gull and goose. We hoped to find rare visitors who nest much further north. In previous years we’ve seen a Snow Goose, three Ross’s Geese, and two Greater White-fronted Geese in the Park. This time we only found a Cackling Goose, a much smaller relative of the abundant Canada Geese. About dozen gulls visit the Park on most late winter days, with larger pink-legged Herring Gulls out numbering the yellow-legged Ring-billed Gulls. The floods brought hundreds more Ring-bills to the Park, but so far no rarer gulls, like Glaucous, Great-black Backed, or Thayer’s. (We’ve never seen those in the Park, but we can always hope.)
On Tuesday, another warm front brought south winds and heavy rains to our neighborhood, so the fields should stay flooded for a few more days. We’ll return to Columbus Park to see what migrant birds rode the winds to our neighborhood. To read about what we find, you can check our eBird lists for Columbus Park.