Two nationally known children’s author/illustrators from Maine put their talents on the line during a “draw off” Saturday, daring children to come up with an idea that defied their efforts to illustrate it.

Chris Van Dusen, who wrote and illustrated “The Circus Ship,” and Scott Nash, who wrote and illustrated “Shrunken Treasures,” stood before an audience beneath a tent in Portland’s Monument Square. The event was held on the closing day of the Maine Lit Fest, a celebration of books presented by the Maine Writers and Publishers Alliance and the Colby College creative writing program.

Children in the audience gave Van Dusen and Nash challenging subjects, from ants carrying trombones to “a burger unicorn.”

As the drawing began, Nash encouraged the kids to stump them. “Let’s get messy.”

Hands shot up, and for the next 30 minutes, the two drew.

Bert Butler, 9, of Nobleboro, asked them to draw the Titanic. The artists turned their backs and started sketching. Within minutes, Van Dusen drew the Titanic, sunk beneath the water, the iceberg still standing. Nash’s Titanic was still afloat, about to crash into the ice.

Nadia Doyon, 8, of Lewiston, asked for a burger unicorn.

“Did you say ‘a burger unicorn?’ ” Nash asked with a puzzled face. The girl nodded. The audience laughed. Nash came up with a hamburger with a protruding horn; Van Dusen’s sketch was of a fluffy tail and a burger.

Naija Clark, 8, of Yarmouth, asked for a giraffe eating a lollipop. Jasper Whalen, 3, of Portland, wanted ants carrying a trombone.

“How many ants?” Nash asked.

The blond youngster showed five fingers. More laughter. Within minutes, there were different versions of ants carrying a huge trombone.

Margaret Madden, 10, of Falmouth, asked for a pirate’s birthday party. Van Dusen sketched a pirate about to scarf down a huge slice of cake, its candles lit. Nash drew a scary pirate with a cake shaped like a skull.

When the drawings were done, the artists autographed their sketches and handed them out to the kids.

Nash is executive director of the Illustration Institute of Portland, which helps create awareness of illustrators by offering exhibitions. Nash has illustrated more than 50 children’s books, including the “Flat Stanley” books written by Jeff Brown. He also has designed the logos for Nickelodeon’s “Nick at Nite,” “Nick Jr.”, and “Comedy Central.” He also wrote and illustrated “The High Skies Adventures of Blue Jay the Pirate,” and “Tuff Fluff: The Case of Duckie’s Missing Brain,” and founded the illustration program at the Maine College of Art.

Van Dusen said this was their third drawing contest, and joked that their sketches “would not be pretty.” He’s best known for “The Circus Ship,” and “Down to the Sea with Mr. Magee.” His latest book is “Big Truck, Little Island,” which has sold out. The book has just been reprinted and will soon be available in stores, he said. He has also illustrated for other authors, including the popular series of “Mercy Watson” books by Kate DiCamillo.

The event aims to encourage children to create, Nash said, adding he loves ideas that come from youngsters. He was a bit stumped by the unicorn hamburger, he said.

“I didn’t do it justice, but the idea was fantastic,” Nash said. The idea is to keep it moving and hopefully convey to kids that you don’t have to be fussy about drawing.

When children get older, they start to become self critical of their drawing. “I try to get them to scribble first, then draw on top of their scribbles” – that’s when their ideas flourish, Nash said, adding that he wants to make drawing accessible to children, “and make kids think, ‘I can do that too.’ ”

Also at Monument Square Saturday was a book fair featuring Maine books and authors.

The literature festival ran from Sept. 30-Oct. 1 in Waterville, then moved to Portland from Oct. 4-8. It showcased more than 50 Maine authors at different events.

The goal is to promote Maine literature, said Gibson Fay-LeBlanc, executive director of the Maine Writers and Publishers Alliance.

Per capita, Maine is rich with writers “doing quality work at the state level, the regional level and the national level,” he said. Illustrators and authors who have achieved recognition, including Nash, Van Dusen and New York Times bestselling author Rebecca Traister, show up to speak and meet their fans.

They and others are excellent literacy citizens, Fay-LeBlanc said, “meaning they give back to writers, collaborate, show up at events like this.”

Emerson Frost of Portland said she was at the Portland Public Library on Saturday when she wondered what the tent was for. She crossed Congress Street and was pleased to find the festival. “It’s cool there’s a whole book fair,” said Frost, who was holding four books. “It’s awesome people are celebrating reading.”