Hackberry Fruits Are Ripening July 17, 2009

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:

Ripening Hackberry fruits (dark green to purple) with pale, fuzzy Hackberry Nipple Galls.

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!

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Here are links more information about Hackberries:

• What Tree Is It?:  Brief description of Hackberry, with photos.
• Wikipedia:  Encyclopedia-style entry about Celtis, the genus that includes our street-side Hackberries.
• Virginia Tech:  Fact sheet about Hackberry trees.
• Texas Beyond History:  Hackberries in Texas archeology.

Collector’s Garden is Open for the Season! March 13, 2009

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:

Children can collect rocks, shells, and fossils in the Collector's Garden.

If you visit the Garden, please follow the rules:

Each child can take home the five best things they find each day.

We stock the Garden with dozens of kinds of rocks and shells, plus shark teeth and other fossils:

You can find all sorts of natural things in the Garden. The exact mix varies from day to day.

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:

• Go here to identify many of the rocks: http://www.saltthesandbox.org/rocks/namesrocksall.htm
• This page has photos of many polished rocks: http://www.saltthesandbox.org/rocks/namespolished.htm

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 eric@saltthesandbox.org.

Upcoming Events: Science and Nature Activities by Neighborhood Nature March 13, 2009

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.)

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So, hope to see you at one of these events!

Finding Fossils We Can’t Collect March 12, 2009

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:

The blocks of limestone make the brick building stronger and more attractive.

Looking closely at the blocks of limestone, there are fossils — evidence of ancient life and clues to the origin of this stone:

The yellow arrow points to a fossil stick coral. The red arrow points to a cross-section view of a brachiopod shell.

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:

Limestone urns and steps on the Refectory's covered terrace.

A closer look at this limestone reveals another common fossil from the ancient sea:

The blue arrows point to fossil crinoid stems. Can you find more examples in this rock?

This type of limestone was quarried in Indiana and has an appropriate name: The Indiana Limestone. The fossils that we see today have been etched out in bas-relief as decades of acid rain dissolved the once-polished surface of the rock.  Go here for more information about fossils found in Indiana Limestone (photos half way down the Web page).

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.

Our family takes this “red dirt” to special events where kids collect its fossils. The next event will be the ESCONI Gem, Mineral, & Fossil Show on March 14-15, 2009:

ESCONI activity: Collecting fossil sea life from weathered Indiana Limestone.

Perhaps we’ll see you there?

Wading Pools in Winter and a New Theory of Dinosaur Extinction February 25, 2009

With today’s temperature in the 50s, I urged Aaron and his friend Matt to explore the backyard instead of the icy expanses of Club Penguin. Eventually they agreed, leaving penguins but not ice behind.

Within minutes they called me to the backyard to record a “discovery” they made. I took some photos and wrote a story to go along with them. (The story was inspired by dinosaur books for kids, which I’ve been reading in preparation for a writing project.)

This only happened because we leave out plastic pools filled with water all winter long. That’s one way we make our neighborhood a better place for outdoor play, a place with No Child Left Inside.

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Aaron and Matt found a dinosaur disaster in our backyard! An imaginary world of dinosaurs and ice was being destroyed.

What had done this terrible thing to Ethan’s old collection of giant plastic dinosaurs? (Ethan is Aaron’s older brother — he’s loved dinosaurs since he was a little kid.)

Can you help us solve this mystery?

Matt carefully studied the ice layers searching for clues:

The ice, unfortunately, held no useful clues to the origin of this disaster.

The team decided to excavate in search of answers. After much digging and clearing of ice, Matt reached into the water with his bare hands. He pulled out a giant rock!

Matt pulled out a giant rock, the cause of the disaster.

It was obvious that a flying rock had shattered this icy world. But where did the rock come from? From outer space? From a volcano? Gradually, the true cause of this disaster became apparent, as the rock struck once again:

The rock struck again -- how did that happen?

The rock then smashed into another pool.

Aaron and Matt imagined the rock had come from space — that was their Theory of Dinosaur Extinction. Should I believe them?

Do you have a better theory? Who will Ethan agree with?

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Thanks to Aaron, who let me tell the story my way, instead of the way it really happened.

With my kids, throwing rocks and smashing ice happen so predictably that they seem almost instinctive. The boys adding characters and plot to the adventure also seemed quite natural. I’ll let evolutionary psychologists explain how these behaviors contributed to our ancestors’ survival on the plains of Africa.

Here’s something that occurred to me — by destroying the ice, the boys found out about the physics of ice, water, and flying rocks. They also learned biology — the smell of dead leaves festering on the bottom of the pools. Smashing things may be the starting point for certain kinds of science, although building things and understanding wholes no doubt have different roots.

And the gender thing: Parents of boys may see more of this than parents of girls, and grown-up boys may better appreciate these images. But if Aaron and Matt’s friend Hannah had been here, she would have been in the thick of it. That’s one reason she’s their friend, and I’m glad they’ve made room for her.

Upcoming Events: Gulls, Pets, Dinosaurs, and Rocks February 18, 2009

Here are some events we will participate in during the next month:

Gull Frolic: Saturday, February 21. Starts 8:00 a.m. at the Winthrop Harbor Yacht Club at the North Point Marina in Winthrop Harbor, IL.  We should see rare gulls and ducks, in addition to more common winter birds. The best part is that when we get cold, we can go inside the warm building to eat, drink hot chocolate, talk to other birders, and see the exhibits. Web address: http://www.lakecookaudubon.org/Gull_Frolic_Illinois.php

Baby Shower at the Animal Care League in Oak Park: Sunday, February 22. The ACL holds their 3rd Annual Baby Shower on Sunday February 22nd from noon until 3 pm at the shelter. This shower is for the kittens and puppies that will soon start showing up at ACL’s doorstep, needing shelter and care as they prepare for adoption. They ask for items to be donated off their wish list (like food, toys, and supplies), but also appreciate monetary donations. (Full disclosure: We adopted our kittens from ACL, and we volunteer there as a family once or twice a week.) Web address: http://www.animalcareleague.org/

Paleofest at Burpee Museum in Rockford, Illinois: Saturday and Sunday, March 7 and 8. OK, let it be known that Ethan and Dad still love dinosaurs, even the ones that didn’t evolve into birds. We’ll go for the lectures by paleontologists from around the country. Families with younger children will enjoy the workshops and museum exhibits. (We’ll look for Rough-legged Hawks and other living raptors as we drive I-290 to Rockford from Oak Park.) Web address: http://www.burpee.org/education/paleofest09.asp

ESCONI Gem, Mineral, and Fossil Show: Saturday and Sunday, March 14 and 15. 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. Dad and one or more of the boys will help run the ESCONI Juniors activities booth days. (We’ll probably go birding on our lunch breaks.) Web address: http://www.esconi.org/esconi_earth_science_club/esconi-gem-mineral-show/

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Will we see you at one of these events?