Geologic Timeline | Teton Geology | Discover Grand Teton

Earth Formed

4.6 billion years ago

The Earth formed from a hot swirling mass of gases. As these gases cooled, they coalesced into solid rocks of the Earth’s crust. (Photo credit: NASA)

Gneiss Formation

2.7-3 billion years ago

Volcanic and sedimentary rocks are deposited in a basin between two tectonic plates. As the two plates collide, heat and pressure metamorphosed the rocks into gneiss. The core of the Teton Range is gneiss.

Granite Formation

2.5 billion years ago

Pressure and heat from the collision of tectonic plates melt the crust. Magma squeezes into weak zones in the gneiss, cools and crystallizes into granite. This resistant rock forms the highest Teton peaks.

Quartzite Formation

1.2-1.5 billion years ago

The quartzite cobbles covering the valley floor formed northwest of the Teton Range. Deeply buried sandstone metamorphosed to form quartzite. Uplift, erosion, and rivers brought the cobbles to the region.

Black Dike Formation

775 million years ago

Vertical east-west cracks formed deep underground as the region stretched. Basaltic magma squeezed into these cracks, cooled and crystallized to form igneous diabase dikes. Look for dikes on the faces of the Middle Teton and Mount Moran.

Flathead Sandstone

500-510 million years ago

Sandy beaches deposited as oceans first advanced over the ancient bedrock to form the bottom layer of the sedimentary strata. Erosion stripped this layer from the high peaks except for the top of Mount Moran.

Deep Oceans

250-500 million years ago

Deep oceans covered the western United States depositing sand, mud and coral reefs that formed sandstone, shale, and limestone. These rocks flank the high peaks of the Tetons to the north, south and west.

Shallow Seas

120–250 million years ago

Shallow seas covered the area episodically, depositing sand and mud. When the seas retreated, coastal marshes and sand dunes formed. These sedimentary rocks outcrop around the edge of the Tetons.

Sevier Orogeny

70–120 million years ago

The Farallon plate slams into and underneath North America compressing the western United States. Sedimentary rocks crumple and fold like a rug on the floor beginning in the west and sliding eastward.

Laramide Orogeny (Rocky Mountains)

50–70 million years ago

The Farallon plate continues to collide with North America compressing the western United States. Folds and faults push up mountain ranges such as the Colorado Rockies, the Wind River and Gros Ventre ranges.

Absaroka Range

45–50 million years ago

The Farallon plate, pushed under the North American plate during the orogenies, begins to sink into the Earth’s mantle. Warm mantle material melts through the crust erupting to form the Absaroka Range.

Mountain Building Takes a Break

30-45 million years ago

Tectonic events that formed the Rockies and the Absaroka Range have ended. Erosion continues to wear down the uplifted region, erasing the evidence of past uplifts and depositing debris across the region.

Western Expansion

17-30 million years ago

West of the Rockies, North America stretched and cracked to form the fault-block mountain ranges of the Basin and Range province. The distance between Reno, NV and Salt Lake City, UT doubles!

The Yellowstone Hotspot

17 million years ago

The magma or hotspot under Yellowstone today started near the Oregon, Idaho and Nevada border. Magma melted the crust, erupted and collapsed as a caldera. The Snake River Plain traces the calderas to Yellowstone.

Western Expansion Continues

10-17 million years ago

West of the Rockies, North America stretched and cracked to form the fault-block mountain ranges of the Basin and Range province. The distance between Reno, NV and Salt Lake City, UT doubles!

Teewinot Lake

10–12 million years ago

A shallow lake covered the region depositing layers of limestone, clay and volcanic ash. The Teton fault began to move when the lake was present. The white patches visible on Shadow Mountain are lake deposits.

Beginning of the Teton Range

10 million years ago

Regional stretching and heat from the Yellowstone hotspot fractured the Earth’s crust generating earthquakes on the Teton fault and the rise of the Teton Range beginning about 10 million years ago.

Teewinot Lake

7.5–10 million years ago

A shallow lake covered the region depositing layers of limestone, clay and volcanic ash. The Teton fault began to move when the lake was present. The white patches visible on Shadow Mountain are lake deposits.

Teton Range Uplift Continues

4.5-7.5 million years ago

Regional stretching and heat from the Yellowstone hotspot fractured the Earth’s crust generating earthquakes on the Teton fault. Each earthquake breaks the ground by about ten feet building the range bit by bit.

Kilgore Tuff

4.5 million years ago

The magma plume, or hotspot, under Yellowstone, has erupted many times depositing volcanic ash in layers called tuffs. The outcrop halfway down the slope of Signal Mountain is the Kilgore tuff.

Teton Range Uplift Increases

2.0-4.5 million years ago

Regional stretching cracked the Earth’s crust to form the Teton fault. As the Teton Range moved past the Yellowstone hotspot, magma heat further stretched the crust and the range rose more rapidly.

Huckleberry Ridge Tuff

2.0 million years ago

The magma plume, or hotspot, under Yellowstone, has erupted many times depositing volcanic ash in layers called tuffs. The outcrop near the top of Signal Mountain is the Huckleberry Ridge tuff.

Pleistocene Ice Age

250,000-2 million years ago

The Pleistocene epoch began approximately 2 million years ago. Vast ice sheets repeatedly covered much of the northern hemisphere including the area that is now Grand Teton National Park during this time.

Interglacial Period

170,000-250,000 years ago

An interglacial period is a period of warmer global temperatures between periods of glaciation. During an interglacial period, glaciers retreat and vegetation spreads across the landscape.

Bull Lake Glaciation

120,000–170,000 years ago

Little evidence of the Bull Lake glaciation remains. The more recent Pinedale glacial period buried or eroded much of the older landscape. Timbered Island is a glacial moraine of Bull Lake age.

Interglacial Period

50,000-120,000 years ago

An interglacial period is a period of warmer global temperatures between periods of glaciation. During an interglacial period, glaciers retreat and vegetation spreads across the landscape.

Pinedale Glaciation

14,000-50,000 years ago

Pinedale glaciers gouged depressions on the valley floor and deposited glacial moraines around the edges. The glaciers melted forming today’s valley lakes, such as Jenny and Jackson, dammed by the moraines.

Interglacial Period

1350 AD-14,000 years ago

An interglacial period is a period of warmer global temperatures between periods of glaciation. During an interglacial period, glaciers retreat and vegetation spreads across the landscape.

Little Ice Age

1350-1850 AD

The glaciers found today in the Teton Range formed during a period of global cooling known as the Little Ice Age.

1850 AD to present

From the 1850s to the present, we have been in an interglacial period. Little Ice Age glaciers are retreating. The Teton Glacier has lost up to 40% of its surface area since the 1960s.