Forbes Shale facts for kids

Quick facts for kids Forbes Shale Stratigraphic range: Coniacian ~89.8–86.3Ma PreЄ Є O S D C P T J K Pg N ↓
Type	Formation
Unit of	Asuncion Group
Underlies	Kione Sands
Overlies	Funks Shale
Thickness	1,300 ft (400 m)
Lithology
Primary	Shale
Location
Coordinates	38°36′N 122°00′W / 38.6°N 122.0°W / 38.6; -122.0
Approximate paleocoordinates	42°48′N 86°30′W / 42.8°N 86.5°W / 42.8; -86.5
Region	California
Country	United States
Extent	Sacramento Valley

The Forbes Shale is a special type of rock layer found in northern California, United States. It's like a giant history book made of stone! This rock formation is located in the Sacramento Valley, especially near the Sutter Buttes in Sutter County, California. Scientists study the Forbes Shale to learn about ancient life.

The rocks in the Forbes Shale hold fossils that are incredibly old. These fossils date back to the Coniacian stage of the Late Cretaceous period. This means the fossils are from about 89.8 to 86.3 million years ago!

Discovering Ancient Life in the Forbes Shale

The Forbes Shale is famous for the many different kinds of fossils found within its layers. These fossils help scientists understand what life was like in this area millions of years ago. Most of the fossils are from creatures that lived in the ocean.

Bivalve Fossils: Ancient Clams and Oysters

Bivalves are a type of sea creature with two shells, like modern clams, oysters, and mussels. Many different kinds of ancient bivalves have been found in the Forbes Shale. They tell us about the seafloor environment long ago.

• Cladoceramus undulatoplicatus
• Glycymerita veatchii
• Inoceramus subundatus
• I. Inoceramus vancouverensis
• I. aff. chicoensis
• I. aff. klamathensis
• I. aff. whitneyi
• Parallelodon (Nanonavis) brewerlanus
• Pseudomelania colusaensis

Gastropod Fossils: Snails of the Past

Gastropods are another group of sea creatures, often called snails. They usually have a single, coiled shell. The Forbes Shale contains fossils of various ancient snails that once crawled along the ancient seafloor.

• Bernaya (Protocypraea) kayei
• Biplica obliqua
• Dentalium (Entalis) whiteavesi
• Pseudomelania colusaensis
• Tessarolax distorta
• Volutoderma californica

Ammonite Fossils: Extinct Cephalopods

Ammonites are perhaps the most exciting fossils found here. They were ancient marine animals related to modern squids and octopuses, but they lived inside a coiled shell. Ammonites are excellent "index fossils," meaning they help scientists figure out the exact age of the rocks.

• Baculites chicoensis
• B. inornatus
• Desmophyllites diphylloides
• Eupachydiscus arbucklensis
• E. willgreeni
• Eutrephoceras campbelli
• Lytoceras (Gaudryceras) alamedense
• Nowakites dobbinsi
• N. rumseyensis
• Oxybeloceras petrolense
• Parapachydiscus cortinaensis
• Puzosia (Holcodiscoides) gorrilli
• Puzosia (Parapuzosia) arenaica
• Baculites sp.
• Canadoceras sp.
• Hauericeras sp.