The anatomy of an earthquake

Professor Iain Stewart tells us more about the anatomy of an earthquake.

Boulder clay

Boulder clay is a deposit of clay, and contains often more boulders. Boulder clay is formed in and beneath glaciers and ice-sheets wherever they are found. The clay is scraped from the top layer of older rock by the movement of an ice sheet. An ice sheet pushes rocks, boulders and everything else in its path, which in turn wears the rock into silt-like grain.

Pleistocene sand landscape

The glacial deposits in the Netherlands.

Alluvial fans are fan-shaped deposits of water-transported material (alluvium).

Cross-section of an ice lob with push moraines, sandr and boulder clay.

Geological time scale

The geological time scale is the geologic history of the planet from formation to the present. 

The geologic time scale is used by geologists, paleontologists, and other earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history. 

The geologic time scale starts with large divisions of time called eons and is subdivided into successively smaller units of time based on dominant lifeforms, extinction events, even climate.  

Geological time scale
Cenozoic	Quaternary period	Holocene epoch	10,000 years
		Pleistocene epoch	1.8 million years
	Tertiary period	Pliocene Miocene Oligocene Eocene Palaeocene	65.5 million years
Mesozoic			252 million years
Palaeozoic			542 million years
Precambrian			4.6 billion years

How Old Is the Earth?

VIDEO - How Old Is the Earth?

Jill Schneiderman, professor of earth science and geography, puts human existence into perspective in this lecture about "Deep Time." A Two-Minute Lecture at Vassar College.