Question

what is igneos and sedimentary rocks

Answer 1

the lowermost region of the soil is which are of bigger size are commonly called as igneous and sedimentary rock

Answer 2

Sedimentary Rock
These rocks are formed by the accumulation fo sediments.
Sandstone is a common sedimentary Rock. It may be yellow, brown ,red, and pink in colour. When the lowest layers of sediment consisting of pebbles, sand and gravel harden ,they form conglomerate. Limestones are formed from animal and plant remain. Shale is made up of clay and mud particles. Shale is a smooth sedimentary rock. It is used to make tiles and bricks. Sedimentary rocks contain remains of plants and animals. These remains are called Fossils.Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in four main ways: by the deposition of the weathered remains of other rocks (known as 'clastic' sedimentary rocks); by the accumulation and the consolidation of sediments; by the deposition of the results of biogenic activity; and by precipitation from solution.

Sedimentary rocks include common types such as chalk, limestone, sandstone, clay and shale.

Sedimentary rocks cover 75% of the Earth's surface.

Four basic processes are involved in the formation of a clastic sedimentary rock: weathering (erosion)caused mainly by friction of waves, transportation where the sediment is carried along by a current, deposition and compaction where the sediment is squashed together to form a rock of this kind.

Sedimentary rocks are formed from overburden pressure as particles of sediment are deposited out of air, ice, or water flows carrying the particles in suspension.

As sediment deposition builds up, the overburden (or 'lithostatic') pressure squeezes the sediment into layered solids in a process known as lithification ('rock formation') and the original connate fluids are expelled.

The term diagenesis is used to describe all the chemical, physical, and biological changes, including cementation, undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface weathering.

Note:   The above text is excerpted from the Wikipedia article "Sedimentary rock", which has been released under the GNU Free Documentation License.



Igneous Rock
The word igneous means 'firey'. Igneous rocks are formed by the cooling of magma. The hot , liquid rock that lies below the earth crust is know as magma.Igneous Rocks

There are places on Earth that are so hot that rocks melt to form magma. Because magma is liquid and usually less dense than surrounding solid rock, it moves upward to cooler regions of the Earth. As the magma loses heat, it cools and crystallizes into an igneous rock. Magma can cool on the Earth's surface, where it has erupted from a volcano (extrusive rock) or under the Earth's surface, where it has intruded older rocks (intrusive rock).

The composition of magma is limited to the eight common elements of the earth's crust. These elements combine within a melt to form silicate minerals, the most common minerals of igneous rocks. These silicate minerals include feldspars (plagioclase feldspar, potassium feldspar), quartz, micas (muscovite, biotite), pyroxenes (augite), amphiboles (hornblende), and olivine. These minerals make up over 95% of the volume of the common igneous rocks, making igneous rocks easy to identify.