Physical Geology Introduction



The volume of water on Earth is estimated to 
be about 1.36 billion cubic kilometers with:

		97% in the oceans
		 2% in glaciers
		 l% in streams, lakes, ground 			
		water,  and the atmosphere

The Hydrologic Cycle

Evaporation: liquid to vapor

Transpiration: release of water vapour from 

Condensation:  As water vapour rises, it cools 
and eventually condenses

Precipitation:  Rain, snow and hail

Surface runoff: Sheet wash or channels

Percolation: migration from surface down

Ground water:

Running Water

Streams modify their channels

Gradient - slope over which the stream flows

The ULTIMATE BASE LEVEL is sea level - 
streams will not erode their base below base 

There may be temporary base levels which 
control the behavior of segments of a stream 
- a dam, for example

Properties of Moving Water

Discharge = Width x Depth x Velocity                
measured in cubic feet/second

An increase in discharge will result in an              
increase in all three parameters -- unless one 
of more of the parameters has been fixed.

Streams carry sediment as part of the 
SUSPENDED LOAD or as part of the BED 

In general, the suspended material is finer 
than the bed load and is transported faster 
than the bed load material.

As velocity changes, for example, material in 
the bed load may be suspended and 
transported with a higher velocity.

The COMPETENCY of a stream is a measure 
of the largest particle it can transport in the 
suspended load.

The CAPACITY is a measure of the total 
suspended load.

In addition, streams can carry ions in 
solution - the CHEMICAL LOAD.

Imagine constructing a dam across a river
Above the dam the river begins to deposit 
material as it adjusts to the new base level
Below the dam erosion can occur at the base 
of the dam.  A lake forms behind the dam - 
becomes a temporary base level

Environments of Deposition

The preservation potential addresses the 
likelihood that deposits will be preserved in 
the rock record.

Continental - relatively low preservaton 

	Alluvial Fans

	Fluvial (River) Systems

	Lacustrine Systems - Lakes

Transitional Systems - beaches, barrier 
islands, washover fans, etc.


	pelagic component (air fall plus material in 
	the water column)

	turbidity currents - adds a terrestrial 
	component to the deep sea sediment
	calcium carbonate compensation depth -