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Cretaceous geology of WyomingFluvial depositsGeologic formations of North DakotaGeologic formations of Wyoming

Lance Formation

Adapted from Wikipedia · Explorer experience

A scenic view of the Lance Formation, a natural rock formation along Cow Creek in Wyoming.

Discover the Lance Formation

The Lance Formation is a special group of rocks from a very old time called the Late Cretaceous, about 69 to 66 million years ago. It is found in the western parts of the United States, mostly in Wyoming. People named it after a place called Lance Creek in Wyoming.

This rock formation is very important for scientists. Why? Because it is full of fossils! Fossils are like nature’s time capsules. They show what plants and animals looked like long, long ago. The Lance Formation helps us learn about life near the end of something called the Mesozoic era.

The rocks in the Lance Formation look different in different places. In North Dakota, they are about 90 meters (300 feet) thick. But in parts of Wyoming, they can be almost 600 meters (2,000 feet) thick! These rocks were formed by old rivers on a flat land near the edge of a big sea called the Western Interior Seaway. The weather back then was warm and wet, with lots of rain.

One of the coolest things about the Lance Formation is all the amazing fossils hidden inside. Scientists have found bones from many different creatures, including birds, pterosaurs like Quetzalcoatlus, fishes, mammals, and even reptiles such as crocodiles and lizards. Some fossils come from animals that lived in water, like frogs and salamanders. Others show that the sea was close by.

The Lance Formation also has fossils of many dinosaurs. Some of these dinosaurs had thick, bony plates on their bodies, called ankylosaurs. There are also fossils of early birds, which help us understand how birds today might have evolved from dinosaurs. All these fossils tell a story about life on Earth millions of years ago, making the Lance Formation a treasure trove for scientists and dinosaur lovers alike.

Images

A scientific diagram showing the layers of rock and coal seams in the Powder River Basin, helping us learn about Earth's history.
Fossil tooth of Pectinodon, an ancient creature from the dinosaur era.
A scientific illustration of the Tyrannosaurus rex, showing what this famous dinosaur may have looked like.
Illustration of Ankylosaurus magniventris, a armored dinosaur from the Cretaceous period of North America.
Illustration of Edmontonia rugosidens, an armored dinosaur from the Late Cretaceous period.
An artist's drawing of Leptoceratops, a small plant-eating dinosaur from the Late Cretaceous period of North America.
An artist’s drawing of Nedoceratops, a horned dinosaur from the Late Cretaceous period of North America.
A scientific artist's reconstruction of Pachycephalosaurus, a type of dinosaur that lived millions of years ago.
Scientific illustration of Torosaurus latus, a horned dinosaur from the Late Cretaceous period of North America.
Illustration of a young Triceratops dinosaur, created by artist Tom Parker.
A pencil drawing of Edmontosaurus annectens, a duck-billed dinosaur that lived during the Late Cretaceous period in North America.
An artist’s reconstruction of the ancient dinosaur Stygimoloch, showing its distinctive head and body.

This article is a child-friendly adaptation of the Wikipedia article on Lance Formation, available under CC BY-SA 4.0.

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