Leo Geo and His Miraculous Journey Through the Center of the Earth by Jon Chad*

In comic-style, readers can learn about the different layers of the earth and other interesting science facts.  Some encounters are fantastical but make the reading more fun!
Points to discuss: Science is the "ultimate answer" to every question.  Old earth view is promoted.
*Highly recommend.

How To Dig a Hole to the Other Side of the World by Faith McNulty illustrated by Marc Simont*

A great book to share when a child is curious what is inside the earth.
Not overly didactic in style but one learns a lot!
*Highly recommend.

National Geographic Readers series by various authors *

These books are full of photographs and lots of nonfiction text features.
Features: table of contents, labels, word definitions on a page, close ups, section heading, picture captions, maps, charts, diagrams, picture glossary,word pronunciations, "stump your parents" questions in some books, jokes/riddles.
Five different levels for every reading level: Pre-readers, level 1 (starting to read), level 2 (reading independently), level 3 (fluent reader) and level 4 (chapter books).
Some titles for Level 1- Trains by Amy Shields; Frogs! by Elizabeth Carney; Dinosaurs by Kathy Weidner Zoehfeld; Storms by Miriam Busch Goin
Some titles for Level 2- Sharks! by Anne Schreiber; Rocks and Minerals by Kathleen Weidner Zoehfeld; Tigers by Laura Marsh; Lizards by Laura Marsh
Highly recommend.

Earthshake Poems from the Ground Up by Lisa Westberg Peters illustrated by Cathie Felstead

A great book that brings poetry/language arts and science together.  Twenty two poems about geology.. . end notes explain more about the science behind each poem.