Diligencia Formation facts for kids

Quick facts for kids Diligencia Formation Stratigraphic range: Late Oligocene-Early Miocene (Arikareean) ~25–20.4Ma PreЄ Є O S D C P T J K Pg N ↓
Type	Formation
Overlies	Proterozoic augen gneiss (basement) Maniobra Formation (in the north)
Thickness	1,500 m (4,900 ft)
Lithology
Primary	Conglomerate, sandstone, siltstone, limestone
Other	Interbedded basalt and andesite
Location
Coordinates	33°30′N 115°42′W / 33.5°N 115.7°W / 33.5; -115.7
Approximate paleocoordinates	32°12′N 107°30′W / 32.2°N 107.5°W / 32.2; -107.5
Region	California
Country	United States
Extent	Orocopia Mountains
Type section
Named by	Crowell
Year defined	1975

The Diligencia Formation is a special type of rock layer found in the Orocopia Mountains in southern California. Geologists call it a "formation" because it's a distinct set of rocks that formed around the same time. This formation holds amazing clues about ancient life, especially mammal fossils, from about 25 to 20 million years ago. This time period is known as the Late Oligocene to Early Miocene epochs.

What is the Diligencia Formation?

The Diligencia Formation is made up of rocks that formed on land, not in the ocean. It was first described by a scientist named Crowell in 1975. The rocks tell us about ancient rivers, lakes, and even volcanic activity.

You can find different kinds of rocks here:

• Conglomerates: These are rocks made of many different sized pebbles and stones cemented together. Imagine a dried-up riverbed!
• Sandstones: These are made from sand grains, just like the sand you might find at a beach or in a desert.
• Siltstones: These rocks are made of very fine particles, even smaller than sand. They often form in calm water, like the bottom of a lake.
• Limestones: These rocks often form from the shells and skeletons of tiny sea creatures, but in this case, they formed in ancient lakes.

Mixed in with these rocks are layers of volcanic rock, like basalt and andesite. These are rocks that cooled from lava flows. Scientists have studied these volcanic rocks and found they are about 21 to 24 million years old. There are also "sills" and "dikes," which are places where magma (molten rock) pushed into cracks in the older rocks and then cooled.

Ancient Animals: Fossil Discoveries

The Diligencia Formation is famous for the fossils it contains, especially those of ancient mammals. These fossils help scientists understand what life was like millions of years ago in California.

Some of the cool mammal fossils found here include:

• Artiodactyls: These are a group of hoofed animals that have an even number of toes. Think of modern deer, pigs, or hippos.
  • Merycoidodontidae: This is a family of extinct (no longer living) mammals that looked a bit like pigs or sheep.
    • Merychyus cf. minimus: This is a specific type of Merychyus, a small, plant-eating animal that roamed the ancient landscapes.

These fossils are like puzzle pieces that help us picture the ancient environments and the creatures that lived there so long ago!