"The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya.<span> <span>Wikipedia."
https://www.google.com/search?q=He+Silurian+period+occurred&rlz=1C1RUCY_enUS760US760&oq=He+Silurian+...
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1. Tiltmeter matches with <span>"The _____ suggests that the ground has risen about 2 inches."
2. </span><span>Richter scale: </span>"People in the cafeteria felt the quake, but those in the conference room didn't. The earthquake magnitude must've been around 3 on the _____."
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3. </span>Mercalli intensity scale: <span>"If you want to measure the earthquake based on the level of damage incurred, use the _____."
4. S</span>eismograph: <span>"The _____ records P waves first, then S waves."
5. C</span>orrelation Spectrometer (COSPEC): "Look! That volcano is emitting smoke! Grab your _____ and measure the sulfur dioxide content."
6. Moment Magnitude Scale: <span>"I would use a _____ to measure the magnitude of earthquakes that occur over large areas." </span>
