Nugget Sandstone facts for kids

Quick facts for kids Nugget Sandstone Stratigraphic range: Norian-Toarcian ~220–180Ma PreЄ Є O S D C P T J K Pg N
Type	Geological formation
Unit of	Glen Canyon Group
Underlies	Carmel Formation
Overlies	Chinle Formation
Thickness	200 m (660 ft)
Lithology
Primary	Sandstone
Other	Mudstone, siltstone
Location
Coordinates	40°24′N 109°18′W / 40.4°N 109.3°W / 40.4; -109.3
Approximate paleocoordinates	27°24′N 46°36′W / 27.4°N 46.6°W / 27.4; -46.6
Region	Colorado, Idaho, Utah
Country	United States
Extent	Colorado Plateau

The Nugget Sandstone is a special rock layer found in the western United States. You can see it in places like Colorado, Idaho, and Utah. This rock formation formed a very long time ago, between the Late Triassic and Early Jurassic periods. That's about 220 to 180 million years ago!

Scientists study the Nugget Sandstone to learn about Earth's past. It's famous because it holds amazing clues about ancient life. These clues include fossil tracks left by theropod dinosaurs and other creatures.

What is the Nugget Sandstone?

The Nugget Sandstone is mostly made of sandstone. This means it formed from sand that was pressed together over millions of years. It also contains some mudstone and siltstone. These types of rocks tell us about the environment where the sand was deposited.

Scientists believe this area was once a huge desert with giant sand dunes. The way the sand layers are stacked, called "cross-stratification," shows how wind blew the sand around. Sometimes, ancient rivers or lakes might have also been present.

Nugget Sandstone near Red Fleet Reservoir, Uintah County, Utah. The uniform sand grains and large slanted layers show it was once a big sand dune.

You can often see special lines in the rock called "bounding surfaces." These lines show where wind eroded the top of an old sand dune before a new one formed on top. It's like seeing the ancient desert landscape frozen in time.

This picture of Nugget Sandstone shows a line where one ancient sand dune was partly worn away by wind before another dune formed on top.

Ancient Animals and Their Traces

The Nugget Sandstone is a treasure chest for paleontologists. They have found many different kinds of fossils here. These fossils help us understand what life was like millions of years ago.

Real Fossils: Bones and More

Sometimes, scientists find actual bones or parts of animals. These are called body fossils. In the Nugget Sandstone, they have found remains of:

• Theropods: These were meat-eating dinosaurs, like the famous T-Rex, but much older and smaller.
• Sphenosuchians: These were ancient relatives of crocodiles.
• Drepanosaurids: These were strange reptiles with grasping tails, possibly living in trees.
• Sphenodontians: These are a group of reptiles that include the modern-day tuatara.

One very important discovery is a flying reptile called Caelestiventus.

Other fossils found include:

• Rhynchosauroides sp.
• Lepidosauria indet. (This means an unknown type of lizard or snake-like reptile)

Trace Fossils: Footprints and Tracks

Even more common than bones are "trace fossils," also known as ichnofossils. These are not parts of the animal itself, but signs of its activity. Think of them as clues left behind! In the Nugget Sandstone, scientists have found many amazing trace fossils, especially footprints.

These footprints tell us about the size of the animals, how they walked, and even what they might have been doing. For example, some tracks show where a dinosaur walked across a muddy or sandy surface that later turned into rock.

This is a Eubrontes track, likely made by a theropod dinosaur, found in the Nugget Sandstone at Red Fleet State Park, Utah.

Some of the trace fossils found here include:

• Batrachopus sp.
• Brachychirotherium sp.
• Brasilichnium sp.
• Cochlichnus sp.
• Diplichnites sp.
• Grallator (Eubrontes) (These are often dinosaur footprints!)
• Gwyneddichnium sp.
• Octopodichnus sp.
• Otozoum sp.
• cf. Paleohelcura sp.
• Pterichnus sp.
• Scoyenia sp.
• Treptichnus sp.
• ?Acanthichnus sp.
• ?Apatopus sp.

These tracks give us a peek into the ancient world of the Nugget Sandstone, showing us where dinosaurs and other creatures walked millions of years ago.