i08a_earthstructure

i08a_earthstructure - Creation of Earth Earth history...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Earth history, structure, and rock cycle Creation of Earth • 4.5 – 4.6 billion years ago – Same as other planets – Accumulation of interplanetary debris and dust Mostl ithin 200 300 mil ear – Mostly within 200 – 300 mil. years – Oldest rocks found: ~ 4 bil. years • Earth is tectonically active – No young impact craters – Instability and diversity of upper part (crust) • Earth history •Eon –Era + Pid + Period > Epoch Seismic waves • Information about Earth’s material and structure • Elastic – Ex.: striking a bell + Sound wave + Bell vibrates • 2 kind of waves – p-waves
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 • p-waves – Primary waves – Longitudinal waves Compressional a e – Compressional waves – Back-and-forth motion in direction of disturbance – Speed ~ 1.5 – 8 km/sec – Propagate through fluids • s-waves – Secondary waves – Shear waves Trans erse a e – Transverse waves – Perpendicular to direction of disturbance – 0.8 – 5 km/sec – Cause sinusoidal movement – Do NOT travel through fluids • Seismology – Study of seismic waves – Wave velocity related to density of material a es cannot penetrate fl id – s-waves cannot penetrate fluids – Reflection of waves along boundaries – Earthquakes – Nuclear (and other bombs) explosions – Generate waves for geologic study of underground
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 9

i08a_earthstructure - Creation of Earth Earth history...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online