Daily Dose of Happiness US # 14 - Chert in Missouri
Chert, also known as flint, is one of the most abundant rocks in Missouri. It is a hard, glasslike, brittle sedimentary rock composed of finely crystalline quartz and its chemical base is silica (SiO2). The presence of impurities gives the stone colors other than white.
Missouri chert is usually white, gray or tan, but almost any colour is possible, depending on chemical variations in the stone and the details of its formation. The primary type of chert found in the area of West Tyson park is known as 'Burlington chert' who's colour varies from white to gray or tan. Banding and mottling may be present. The surface of this chert usually has a 'waxy' feel and luster and may have chipped, somewhat sharp edges even before being worked into tools.
Certain colours have their own special names. Jasper, for example, is reddish, orange or yellow chert.
Agate is banded in many colours and is sometimes translucent.
The Missouri General Assembly chose Mozarkite, a colourful chert with a banded pattern of red, pink and gray, to be the state rock.
How was Chert was formed:
Much of Missouri is underlain by carbonate rocks - limestones and dolomites - that formed from sediments on the bottoms of ancient seas. This is the thick, layered rock we see along road cuts and river bluffs. Chert is associated with almost every type of limestone and dolomite in Missouri. It appears as globular-shaped "nodules" and "beads," and in pockets and veins of various sizes and shapes interbedded with the limestone.
Geologists are unsure exactly how the chert formed in the limestone. Two possibilities are that oceans deposited silica along with the calcium carbonate shells of marine life, and the chert formed into sedimentary rock along with limestone. Another theory holds that chert formed later, when silica-rich ground water permeated spaces in the limestone. Whatever its origin, chert exists in limestone, and chert nodules, veins and layers are easy to see in road cuts through chert-bearing carbonate rocks.
Chert was once a very useful commodity: Stone Age people used it for making tools as it can be fractured and chipped to create intricate shapes and sharp edges. For thousands of years, chert knives, scrapers, spear and arrow points, drills, hoes, axes, grinding tools and ceremonial objects represented the peak of art and technology.
Early Missourians dug open mines to secure the best chert for making tools. They also traded for special quality stone and stone tools, sometimes over long distances.
Chert was also important for its ability to produce sparks which could start fires and later, to ignite gunpowder in flint-lock firearms.
The posted coordinates will take you to the Trail head of the Flint Quarry Trail in West Tyson Park.
If you choose to follow the trail it will take you to “The Crescent Chert Quarries” where Native American surface miners extracted chert. These aboriginal flint quarries were utilized by pre-historic Peoples for thousands of years, including the People of Cahokia.The Cahokian People actually controlled these quarries to obtain the high quality of flint which was shaped into tools and projectile points. The central portion of the quarries is protected by the West Tyson County Park. These pits and quarry ledges were probably cut during the Middle Woodland Period (ca. AD 100). The pit and quarry ledge features are listed on the National Register of Historic Places. The central portion of the quarries are located at N 38 30.973 W 90 35.161 at an elevation 235 meters.
Logging Requirments for this Earthcache:
Visit the posted coordinates and take a short hike down the Flint Quarry Trail. There are a multitude of examples of Chert at the trail head and along the trail. Find an piece of Chert and email or message me from my profile the answers to these questions:
- Describe the rock’s colour, texture and shape.
- Do you believe the rock is Jasper, Agate or Mozarkite? Why or why not?
- Is Chert sedimentary, igneous or metamorphic?
- Why do you think Chert was useful in making of tools?
Post a picture of yourself or a personal item with the ‘Flint Quarry Trail’ Sign included. (N 38° 30.679' W 90° 35.198')
Please do not pick the flowers or in any way alter the vegetation growing in your the Park. Do not deface or remove any rocks, stones, or other natural/native materials.
This Earthcache is available only during the posted hours: Dawn (1/2 hour before official sunrise) - Dusk (1/2 after official sunset)
MISSOURI DEPARTMENT OF CONSERVATION
ST. LOUIS COMMUNITY COLLEGE
ST. LOUIS COUNTY PARKS