The Hunton Group limestone formed between 450-375 million years ago during the Paleozoic Era as sediments accumulated in shallow seas. These sediments were later lithified into limestone and uplifted during the Pennsylvanian period to form the Arbuckle Mountains. The Hunton Group is exposed in outcrops today and ranges from 100-1000 feet thick, consisting of grey limestone containing marine fossils. Younger Sylvan Shale and Viola Group limestones underlie the Hunton Group, also forming in shallow marine environments.

1. Running head: Geological History of Oklahoma
Arbuckle Mountains: Hunton Anticline Geological History
Christopher Ott
Rose State College

2. GEOLOGICAL HISTORY OF OKLAHOMA 2
Arbuckle Mountains: Hunton Anticline Geological History
Abstract
This paper is a brief summary about the Hunton Group limestone anticline. Included is the
geological history of the Hunton Group limestone and how the Arbuckle Mountains were
formed. This paper also describes rock lithology that makes up the Hunton limestone.
Furthermore, this paper investigates the inferred deposition of the Hunton limestone and the
Principle of Superposition of Strata (pre-folding). A brief geological history of the Sylvan Shale
and Viola Group limestone is also included.

3. GEOLOGICAL HISTORY OF OKLAHOMA 3
Arbuckle Mountains: Hunton Anticline Geological History
The Hunton Group formed during the Paleozoic Era (542 ma – 251 ma). It is +/- 450 ma
and was first deposited during the later Ordovician period. It continued to form through the
Silurian period and into the early Devonian period (450 ma – 375 ma). The Hunton thickness
ranges from 100 to 500 feet thick with a maximum thickness 1,000 feet. The Hunton group is
limestone and is rich with marine fossils like Brachiopods, Trilobites, and Crinoids (Johnson
2008).
The Hunton group was laid down by alternating sea levels which caused thick layers of
sediments to accumulate in shallow seas over a large area (Johnson (2008). The Hunton Group
was eroded away from the northern shelf areas. Eventually, the Hunton Group was buried and
lithified into a limestone.
A study by Johnson (2008) showed: During the Pennsylvanian period, there was crustal
unrest in Oklahoma. Uplifts in Colorado and New Mexico gave rise to the mountain
chain referred as the Ancestral Rockies. Sediments that were deposited in the Arbuckle
were lithified and uplifted to form major mountains, while nearby basins subsided rapidly
and received sediments eroded from the highlands.
The Hunton Limestone is a sedimentary rock. Its color is grey to light grey. Its texture is
smooth with a cryptocrystalline matrix. Its mineral composition is calcite. It also contains many
marine fossils and fossil frags like brachiopods, crinoids, and trilobites. Inclusions consist mainly
of chert nodules and embedded shale fragments. Inferred depositional setting suggest that the
limestone was from a marine environment with a high speed flow.
Below the Hunton Group is the Sylvan Shale and Viola Group limestones. They were
laid down during the middle to late Ordovician period. Similar to the Hunton group, the Sylvan

4. GEOLOGICAL HISTORY OF OKLAHOMA 4
and Violas inferred deposition suggest that they formed from a shallow-marine environment.
These strata can be up to 2,500 feet thick in the Arbuckle Mountains.
Today, the Hunton Group is exposed in some areas. The exposed areas are called
outcrops (Stanley 2008). Outcrops are formations of strata that are exposed at the surface. The
top of the Hunton Anticline surface was eroded across the formation. Erosion later formed the
outcrops that are visible today. These were the last events to happen. The cross section of the
Hunton Anticline illustrates the Hunton Anticline.

5. GEOLOGICAL HISTORY OF OKLAHOMA 5
References
Johnson, K. S. (2008) Geological history of Oklahoma. Educational Publication 9
Stanley, T.M. (2013). The Hunton Anticline Quarry. The Shale Shaker 64(3), 228-237.