Plates are diverging away from each other.

Divergent plate boundaries
 

Keywords: divergent boundaries, rift valley, oceanic basin

Divergent plate boundaries are found on the sea floor were they form ocean ridges. The actual plate boundary is found on rift, which forms along the axis of a ridge it is the center were seafloor spreading begins. The formation of new ocean crust is through high amounts of heat that are produced volcanism and earthquakes associated with these boundaries. The concept of divergent plate boundaries is to make the ocean basin grow wider. Although some form ridges on the ocean floor, some divergent boundaries form on continents. When continental crust begins to separate it forms a long narrow depression called a rift valley. The rifting may cause the formation of a new ocean basin.


References:


Scelsi Hess F., Kunze G., LeslieS. A., Letro S., Millage C., Shrap L., Snow T. (2002). Earth Science: Geology, the Enviroment, and the Universe. New York: NY Glencoe
Ebboney Wilson. (2011). 
Retrieved 2011, from http://geology1a-1.wikispaces.com/Plate+Boundary+images+and+captions
   

Divergent plate boundries

Is the Ocean expanding?

Sea floor spreading

Key words: Ocean ridges, magnetic reversal, magnetometer, paleomagnetism, seafloor spreading.

Magnetic patterns on the seafloor are symmetric in relation to ocean ridges, indicating that ocean crust on either side of the ridge is moving away from the ridge at almost the same rate. During seafloor spreading magma rises and hardens to form new crust which becomes part of the ocean floor. Each cycle of spreading and intrusion results in the formation of another small section of ocean floor, which slowly moves away from the ridge.

Questions: 

1. Are magnetic patterns symmetric in relation to oceanic ridges?
2. What happens during seafloor spreading?
3. What does spreading and intrusuion result in?

References:

Scelsi Hess F., Kunze G., LeslieS. A., Letro S., Millage C., Shrap L., Snow T. (2002). Earth Science: Geology, the Enviroment, and the Universe. New York: NY Glencoe.

Mid ocean ridge Pictures Photo Gallery added by mithunss. Web Hosting by HIOX INDIA. Retrieved, from http://withfriendship.com/user/mithunss/mid-ocean-ridge.php

Did Continents move away from each other?

Pangea, our first continent

Keywords: continental drift, Pangea, Alfred Wegner, Atlantic Ocean.

Continental drift states that the earth’s continents were joined as a single landmass that broke apart and was sent away from each other. The matching of landmasses on continents on opposite sides of the Atlantic Ocean states that one day these two continents were once joined together. Wegner supported the concept of drifting continents, were he observed that some of the rocks of the Appalachian Mountains in the United States shared similar features with rocks in Greenland and Europe. He also mentions similar fossils and ancient climatic data of the same type on continents that are today away from each other.

Questions:

1. What is a continental drift ?
2. What is pangea?
3. What are the two different continents that we found simalar rocks on? 

References:

Logan's dino world. (2010).
Retrieved 2010, from http://www.logansdinoworld.com/pangea.html

Scelsi Hess F., Kunze G., LeslieS. A., Letro S., Millage C., Shrap L., Snow T. (2002). Earth Science: Geology, the Enviroment, and the Universe. New York: NY Glencoe 

Welcome to the Geology Class

This blog is designed for 4th intermidiate Geology students. You will find here activities, announncments, and exam dates concerning the course. Hope we will enjoy the course together.