تبلیغات
Geology Center - Weathering


کدستان
درباره من
سلام من مجید دانشجوی رشته زمین شناسی هستم.هدف این مرکز کمک به دانشجویان و علاقمندان به این دانش است و هم چنان تلاش می کنم تا همیشه مطالب تازه ای از علم زمین شناسی را برای استفاده شما کاربران گرامی قرار دهم.به هر حال اگر در این مرکز کم و کاستی را مشاهده کردید از شما پیشاپیش معذرت می خواهم چون هدف من کپی کردن مطالب وب های دیگر نیست بلکه ارائه مطالبی است که بدست شخص خودم جمع آوری شده است.لطفا مطالبم را مطالعه نمایید و با نظرات خود منو برای قرار دادن مطالب بعدی کمک کنید.همچنین شما می توانید با مراجعه با لینک دعوت به همکاری منو در ارائه هر چه بهتر سایر مطالب وی کمک کنید از همتون ممنونم با تشکر
 
درباره وب




مدیر وب : مجید
پیوندهای روزانه
نظرسنجی
سطح مطالب این وب را چگونه ارزیابی می کنید؟







آمار وب
  • کل بازدید :
  • بازدید امروز :
  • بازدید دیروز :
  • بازدید این ماه :
  • بازدید ماه قبل :
  • تعداد نویسندگان :
  • تعداد کل پست ها :
  • آخرین بازدید :
  • آخرین بروز رسانی :
تماس با ما
Geology Center
The First Weblog Spesial In The Nourth Khorasan
صفحه نخست             تماس با مدیر           پست الکترونیک               همکاری با ما           RSS                  ATOM
دوشنبه دوازدهم تیر 1391 :: نویسنده : مجید

What is weathering?

The process of weathering alters rocks at the earth's surface and breaks them into fine-grained particles of sediment and soil. Weathering is the result of the interactions of air, water, and temperature on rocks and prepares the rock for erosion. Erosion is the movement of the particles by ice, wind, or water. The particles are then transported by that agent until they are deposited to form sedimentary deposits, which can be later eroded again or transformed into sedimentary rocks .

Types of weathering

There are two kinds of weathering: mechanical and chemical.

a) Mechanical weathering

Mechanical weathering is the process by which rocks are broken down into smaller pieces by external conditions, such as the freezing of water in cracks in the rock. Five major processes cause mechanical weathering:

1. Pressure-release fracturing: If a large intrusion is brought to the surface through tectonic uplift and the erosion of overlying rocks, the confining pressure above the intrusion has been released, but the pressure underneath is still being exerted, forcing the rock to expand. This process is called unloading and gives rise to pressure-release fracturing. Because the outer layers expand the most, cracks, or sheet joints, develop that parallel the curved outer surface of the rock. Sheet joints become surfaces along which curved pieces of rock break loose, exposing a new surface. This process is called exfoliation.

2. Frost wedging: Water expands when it freezes. If water accumulates in a crack and then freezes, its expansion pushes the rock apart in a process called frost wedging.

3. Abrasion: Many rocks along a stream or beach are rounded and smooth. The mechanical wearing and grinding of rock surfaces by friction and impact is called abrasion.

4. Organic activity: Less important agents of mechanical weathering include the burrowing of animals, plant roots that grow in surface cracks, and the digestion of certain minerals, such as metal sulfides, by bacteria.

5. Thermal expansion and contraction: Daily temperature changes, especially in those regions where temperatures can vary by 30 degrees centigrade, result in the expansion and contraction of minerals, which weaken rocks.

b) Chemical weathering

Chemical weathering occurs when air and water chemically react with rock to alter its composition and mineral content. For example, feldspar crystals in a volcanic tuff commonly weather to form new clay minerals. Other minerals, such as calcite, dissolve. Quartz, on the other hand, is very resistant to weathering. The most important processes of chemical weathering are dissolution, hydrolysis, and oxidation. Water, carbon dioxide, acids and bases, and oxygen are common substances that cause these processes to decompose rocks.

1. Dissolution: A few minerals dissolve readily in water. Acids and bases often markedly increase the solubility of minerals.

2. Hydrolysis: During dissolution, a mineral dissolves but does not react chemically with the solution. However, during hydrolysis, water reacts with a mineral to form a new mineral with the water incorporated into its crystal structure. Many common minerals weather by hydrolysis. For example, feldspar, the most abundant mineral in the Earths crust, weathers by hydrolysis to form clay.

3. Oxidation: Many elements react with atmospheric oxygen, O2. Iron rusts when it reacts with water and oxygen. Rusting is one example of a more general process called oxidation.

Soils

The layers of weathered particles of earth material that contain organic matter and can support vegetation are defined as soil. Soil can be all or just part of the sedimentary material that covers the bedrock. Soil commonly consists of sand, silt, clay, and organic material. The most fertile soils contain a mixture of sand, clay, and silt as well as abundant amounts of organic matter. Such a mixture is called loam.

Soil profiles

A typical mature soil consists of several layers called soil horizons. The uppermost layer is called the O horizon, named for its Organic component. This layer consists mostly of litter and humus with a small proportion of minerals .





نوع مطلب : مقالات انگلیسی، 
برچسب ها : مقالات انگلیسی زمین شناسی، مقاله انگلیسی درباره هوازدگی، مرکز زمین شناسی سیمانیکس، پیام نور بجنورد،
لینک های مرتبط :


یکشنبه سی ام دی 1397 04:07 قبل از ظهر
Incredible....this is a beneficial web-site.
یکشنبه سی ام دی 1397 03:20 قبل از ظهر
Simply desired to emphasize Now i'm thankful I happened onto your webpage!
یکشنبه سی ام دی 1397 02:28 قبل از ظهر
I value the data on your web site. Kudos.
یکشنبه سی ام دی 1397 02:03 قبل از ظهر
Exceptionally user pleasant website. Enormous details offered on couple of gos to.
یکشنبه سی ام دی 1397 12:20 قبل از ظهر
Wow because this is great work! Congrats and keep it up.
شنبه بیست و نهم دی 1397 09:34 بعد از ظهر
Appreciate it for sharing your excellent webpage.
شنبه بیست و نهم دی 1397 09:11 بعد از ظهر
What's up, neat site you've gotten here.
شنبه بیست و نهم دی 1397 08:55 بعد از ظهر
I love the info on your web sites. Thanks a bunch!
شنبه بیست و نهم دی 1397 08:29 بعد از ظهر
Great looking website. Presume you did a great deal of your very own coding.
پنجشنبه بیست و هفتم دی 1397 06:28 بعد از ظهر
it will always be interesting to read content
پنجشنبه بیست و هفتم دی 1397 06:27 بعد از ظهر
very quickly this website will be famous
سه شنبه بیست و پنجم دی 1397 10:43 قبل از ظهر
Santiago is just how I'm called and my girlfriend doesn't be pleased at just
about all. I've always loved living in colorado. For years she's been working regarding interviewer and she or he
will not change it anytime soon. Fishing is actually of
issues he loves most. My wife and I maintain a website.
You may decide to give it a look here: http://erektion-dk.eu/eronplus.html
یکشنبه بیست و سوم دی 1397 09:05 قبل از ظهر
Hi, Neat post. There is an issue with your web site in internet explorer, may check this?
IE still is the market chief and a huge component to people will omit your
wonderful writing because of this problem.
جمعه بیست و یکم دی 1397 07:30 بعد از ظهر
really nice
جمعه بیست و یکم دی 1397 07:29 بعد از ظهر
extremely helpful info particularly tha last part
جمعه بیست و یکم دی 1397 07:29 بعد از ظهر
ncie post//very neat
جمعه بیست و یکم دی 1397 07:28 بعد از ظهر
excllent webpage
پنجشنبه بیستم دی 1397 03:25 بعد از ظهر
Hello i am kavin, its my first occasion to commenting anyplace,
when i read this paragraph i thought i could also
make comment due to this brilliant article.
پنجشنبه بیستم دی 1397 01:50 قبل از ظهر
Hi there! Quick question that's totally off topic.

Do you know how to make your site mobile friendly? My site looks weird when viewing from my
iphone. I'm trying to find a template or plugin that might
be able to resolve this problem. If you have any recommendations,
please share. Thanks!
دوشنبه هفدهم دی 1397 10:25 قبل از ظهر
It's appropriate time to make some plans for the future and
it's time to be happy. I have read this post and if I could
I wish to suggest you few interesting things or suggestions.
Perhaps you can write next articles referring to this article.
I wish to read even more things about it! I am sure this paragraph has touched all the internet people, its really really fastidious post on building up new blog.
Ahaa, its fastidious conversation on the topic of this piece of writing at this place at this webpage,
I have read all that, so at this time me also commenting at this place.
http://cspan.co.uk
دوشنبه هفدهم دی 1397 07:00 قبل از ظهر
Have you ever thought about adding a little bit more than just your
articles? I mean, what you say is valuable and everything.
However just imagine if you added some great visuals or video clips to give your posts more, "pop"!
Your content is excellent but with pics and clips, this site could
certainly be one of the most beneficial in its field. Very good
blog!
یکشنبه شانزدهم دی 1397 03:24 بعد از ظهر
My partner and I stumbled over here from a different website
and thought I should check things out. I like what I see so now i am
following you. Look forward to looking into your web page for a second
time.
یکشنبه شانزدهم دی 1397 03:24 بعد از ظهر
I'm truly enjoying the design and layout of your website.
It's a very easy on the eyes which makes it much more enjoyable for me to come here and visit more often. Did you hire out a developer to create
your theme? Outstanding work!
شنبه پانزدهم دی 1397 01:32 قبل از ظهر
Hi there! This is kind of off topic but I need some
advice from an established blog. Is it tough to set up your
own blog? I'm not very techincal but I can figure things out pretty quick.
I'm thinking about setting up my own but I'm not sure where to begin. Do you have any tips or
suggestions? Many thanks
پنجشنبه سیزدهم دی 1397 09:41 بعد از ظهر
Now that you learn about video editing along with the things you need you are
ready to begin with your journey of amateur filmmaker to
professional director. " It was President Theodore Roosevelt who had given it the category of White House in 1901. This can be very advantageous to you personally if you're fast learner, with just an endeavor, you might learn all that you wanted to quickly and free.
پنجشنبه سیزدهم دی 1397 03:05 قبل از ظهر
Awesome Website, Carry on the very good job. Thanks for your time.
شنبه هشتم دی 1397 09:30 بعد از ظهر
Maintain the outstanding job !! Lovin' it!
پنجشنبه ششم دی 1397 10:04 بعد از ظهر
You have got the most effective sites.
پنجشنبه ششم دی 1397 07:57 قبل از ظهر
I adore this site - its so usefull and helpfull.
دوشنبه سوم دی 1397 07:14 بعد از ظهر
I love checking your web site. Regards!
 
لبخندناراحتچشمک
نیشخندبغلسوال
قلبخجالتزبان
ماچتعجبعصبانی
عینکشیطانگریه
خندهقهقههخداحافظ
سبزقهرهورا
دستگلتفکر


نمایش نظرات 1 تا 30
 
 
برچسب ها
پیوندها
آخرین مطالب