Flat Landing Brook Formation facts for kids
Quick facts for kids Flat Landing Brook FormationStratigraphic range: Darriwilian, 466–465Ma |
|
|---|---|
| Type | Geological formation |
| Unit of | Tetagouche Group |
| Sub-units | Reids Brook Member, Forthy Mile Brook Member, Roger Brook Member, Moody Brook Member |
| Underlies | Little River Formation |
| Overlies | Nepisiguit Falls Formation |
| Thickness | Unknown |
| Lithology | |
| Primary | Rhyolite flows, hyaloclastics, breccias, hyalotuffs |
| Other | Shale, greywacke, siltstone, iron formation, tholeiitic basalt, alkali basalt |
| Location | |
| Region |  New Brunswick |
| Country |  Canada |
| Type section | |
| Named for | Flat Landing Brook |
| Named by | R.W. Sullivan, 1990; C.R. van Staal et al., 1990 |
The Flat Landing Brook Formation is a special group of volcanic rocks found in Gloucester County, northern New Brunswick, Canada. These rocks formed a very long time ago, about 466 to 465 million years ago. This was during a time called the Darriwilian stage of the Ordovician epoch, when Earth looked very different!
Contents
What is the Flat Landing Brook Formation Made Of?
This formation is mostly made of volcanic rocks. The main types are rhyolite flows, breccias (rocks made of broken pieces), and hyaloclastics. Hyaloclastics are volcanic rocks that form when hot lava shatters as it hits water.
You can also find other rocks here, like basalt (a dark, fine-grained volcanic rock) and tuff (rock made from volcanic ash). There are also smaller amounts of siltstone, greywacke, iron formation, and shale.
Where Can We Find These Rocks?
The Flat Landing Brook Formation is part of a larger group of rocks called the Tetagouche Group. The best place to see these rocks is near Flat Landing Brook itself, between Route 490 and the brook's source. This area is known as the "type locality."
These rocks are found between two other rock formations. Above them is the Little River Formation, which has lots of pillow basalt (lava that cooled quickly underwater, forming rounded shapes like pillows). Below them is the Nepisiguit Falls Formation, which contains crystal tuff and schist. You can see where these different rock layers meet in places like the Brunswick Mines area and along the Nepisiguit River.
Different Parts of the Formation
The Flat Landing Brook Formation is divided into four main parts, each with its own type of rock:
| Formation | Age | Main Rocks |
|---|---|---|
| Reids Brook Member | Middle Ordovician | Rhyolite flows, hyaloclastites, breccias |
| Forty Mile Brook Member | Middle Ordovician | Tholeiitic pillow basalt |
| Roger Brook Member | Middle Ordovician | Tuff and minor porphyritic felsic flows |
| Moody Brook Member | Middle Ordovician | Tholeiitic to transitional mafic fragmental rocks and massive flows |
Was This a Supervolcano?
Scientists believe the Flat Landing Brook Formation came from a huge supervolcano eruption! It's estimated that about 12,000 cubic kilometers (2,900 cubic miles) of volcanic material erupted. This makes it similar in size to famous supervolcanoes like Taupo in New Zealand or the Yellowstone caldera in the USA.
It might even be the largest supervolcano eruption from the entire Paleozoic era! Most of these volcanic rocks were laid down in a very short time, possibly less than two million years.
A large area within the formation, called the Grants Lake pyroclastics, is thought to be the remains of a giant caldera. A caldera is a huge bowl-shaped depression that forms when a volcano collapses after a massive eruption. This ancient caldera might have been about 80 kilometers (50 miles) wide!
Some smaller volcanic rocks, like the Taylor Brook rhyolites, are also found here. These might have come from smaller vents on the edges of the main supervolcano.
