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Rock Timeline
Move from right to left and see the evolution of the area through its rocks.
- 4.6 billion years ago
- The Earth is formed
- 250 million years ago
- Two small continents collide to form the base of present-day China
Gneiss
This is one of the rocks that make up part of the famous Hida Metamorphic Rocks. It formed when the original rock was put under high amounts of heat and pressure. You can see what looks like layers of dark and white minerals. Although they appear like sedimentary layers, these stripes are created when the original rock went under extreme shear stress (i.e. a sliding-squeezing action) that pulled any mineral groups in the original rock into long, flat stripes.
Crystallized Limestone
This is one of the rocks that make up part of the famous Hida Metamorphic Rocks. It was formed when a bed of limestone was recrystallized through intense heat and pressure. These bright white, sparkly rocks stand out on the riverbank, making them easy to spot.
130 million years ago
A big river flowed where dinosaurs and other creatures lived
Mudstone
One of the strata formed during the time of the dinosaurs, this rock is made from layers of mud that hardened and turned into stone over time. Within this stratum you can find many different kinds of fossils, including dinosaur fossils. The rock sample in this exhibition is full of shell fossils.
Conglomerate
One of the strata formed during the time of the dinosaurs, this rock is made of many pebbles over 2mm in size. The rock sample in this exhibition is full of round orthoquartzite pebbles, which formed on the Eurasia continent.
70 million years ago
A huge eruption of magma occurs over a wide area
Welded Tuff (Nohi Rhyolite)
This tuff formed sometime between the extinction of the dinosaurs, and the rise of the mammals, when lapilii (semi-molten pebbles of lava) deposited en masse after a huge eruption. Because of the thickness and hardness of the rock, it can be easily found along the riverbanks of the Ozo River and further downstream.
20 million years ago
Edge of Asian continent separates to form parts of Japan
Welded Tuff
This dark black, glass-like rock is a type of welded tuff, and contains moonstone gems which shine a blue-rainbow color when illuminated. This rock is formed from the violent volcanic eruptions at the location of the splitting Asian continent. Jagged and crushed rocks broken from the explosion, and layers of super-heated ash fell to the ground, welding together to form this rock.
15 million years ago
Deep sea volcanic activity begins, and the Sea of Japan spreads
Volcanic Tuff (Green Tuff)
This volcanic tuff was formed when the Sea of Japan began to form. As the plate began to rift, the hot mantle rose and began erupting as deep-sea volcanos. This activity released volcanic ash into the air, which deposited on the coast, welding together to form this green coloured tuff. It is an easy stone to process, and has been used for various industries in the area.This volcanic tuff was formed when the Sea of Japan began to form. As the plate began to rift, the hot mantle rose and began erupting as deep-sea volcanos. This activity released volcanic ash into the air, which deposited on the coast, welding together to form this green coloured tuff. It is an easy stone to process, and has been used for various industries in the area.
From 400,000 years ago
Mt. Hakusan begins erupting and is still active
Andesite
The top of Mt. Hakusan is made from andesite, essentially solidified lava from many eruptions. The rocks from Mt. Hakusan, which began erupting approximately 400,000 years ago, can be found relatively easily in riverbanks, as the layers of rock beneath Mt. Hakusan are easily eroded. The feature that makes andesite recognizable is its large black and white crystals, which were able to grow big due to the slow cooling time of the lava.