By: Andrea H.

Volcanoes and earthquakes...... YIKES!!!

Here are some pictures of volcanoes.

If you  would like to see more info or pictures on volcanoes click here

Mt. St. Helens before it erupted.

Fault Zone

Sand Dunes

 As you might know sand can only be moved by strong, steady winds. The air must be at least 15 miles per hour to be able to pick up  sand grains! In the Tularosa basin, it is primarily between February and April that the wind is strong enough. These winds are called unidirectional winds because they always move in the same direction, to the southwest to the northeast. As the wind blows, it pushes the sand ahead of it, so individual dunes are slowly moving to the northeast. Sand is not as easy to move as you think. Even very strong winds can't lift the sand any higher than three feet above the ground. As the wind blows, it lifts small sand grains a few feet off the ground, then drops them. When they hit the ground, they bump into other sand grains and cause them to jump up and be caught by the wind. It's almost as if the sand is playing leapfrog, jumping and bumping along. This kind of jumping movement is called saltation. You can see this kind of movement on the windward side of the dune, or the side facing the oncoming wind. But what about the leeward {on or toward the side which the wind is blowing} side of the dune, protected from blowing wind? What causes the sand to move on that side? As the tiny sand grains slowly work their way up the windward dune face, they finally reach the crest, or top of the dune. They fall over the crest and start to pile up because they are protected from the wind. Now gravity steps in to move the dune. As more and more sand grains pile up, the angle of the leeward face becomes steeper and steeper. A pile of loose material, like sand, can only hold a slope of about 34 degrees, gravity pulls the loose sand down. Small avalanches occur. The sand might run down the leeward face like a waterfall, or the whole side might slip at once. When the entire face of the dune slips, it's called slumping.

  Earthquakes!!

are the shaking, rolling or sudden shock of the earth’s surface. Earthquakes happen along "fault lines" in the earth’s crust. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted -- although scientists are working on it!

Most of the time, you will notice an earthquake by the gentle shaking of the ground. You may notice hanging plants swaying or objects wobbling on shelves. Sometimes you may hear a low rumbling noise or feel a sharp jolt. A survivor of the 1906 earthquake in San Francisco said the sensation was like riding a bicycle down a long flight of stairs.

intensity of an earthquake can be measured. One measurement is called the Richter scale. Earthquakes below 4.0 on the Richter scale usually do not cause damage, and earthquakes below 2.0 usually can’t be felt. Earthquakes over 5.0 on the scale can cause damage. A magnitude 6.0 earthquake is considered strong and a magnitude 7.0 is a major earthquake. The Northridge Earthquake, which hit Southern California in 1994, was magnitude 6.7.

Earthquakes are sometimes called tremblers, quakes, shakers or seismic activity. The most important thing to remember during an earthquake is to DROP, COVER and HOLD ON. So remember to DROP to the floor and get under something for COVER and HOLD ON during the shaking.

I hope you enjoyed my web page. If I get another chance to make a web page, I hope you will take time to enjoy it!!!!!