Class 6

Sea waves comes under exogenic force.

Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement.

Frost action is an effective form of mechanical weathering. When water trickles down into fractures and pores of rock, then freezes, its volume increases by almost 10 percent.

Erosion is movement of individual grains, rather than masses, of soil by water or wind. Cumulatively, this persistent grain-by-grain movement can also cause significant damage. Rapid coastal erosion during a period of high surf or a hurricane storm surge can undermine buildings, roads, and other coastal facilities.

Floods are often caused by heavy rainfall, rapid snowmelt or a storm surge from a tropical cyclone or tsunami in coastal areas.

The topsoil is relatively thin but it has most of the soil’s nutrients.Just below the topsoil layer is the subsoil layer. The subsoil may contain some broken down organic matter but it is mostly made of weathered rocks and clay minerals.

Raindrop impact is the primary cause of particle detachment. Raindrops can splash soil particles, moving them up to three feet away. Some of the detached particles float into soil pore spaces.

The dunes were formed by the right combinations of wind, water, and sediment. Creeks and streams brought in large amounts of sediment and sand into the valley. Wind then blew the sand toward the bend in the Sangre de Cristo Mountains, where opposing storm winds helped squeeze the sand into the tall dunes you see today.

[ trăns-vûrs′, trăns′vûrs′ ] A large, strongly asymmetrical, elongated dune lying at right angles to the prevailing wind direction. Transverse dunes have a gently sloping windward side and a steeply sloping leeward side. They generally form in areas of sparse vegetation and abundant sand.

Floods are the most common natural disaster in the United States. Failing to evacuate flooded areas or entering flood waters can lead to injury or death. Floods may: Result from rain, snow, coastal storms, storm surges and overflows of dams and other water systems.