New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

The Dynamic Earth

by: Cathrine Hoeger

The Dynamic Earth ESCI 401

Cathrine Hoeger
GPA 3.67


Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Class Notes
25 ?




Popular in Course

Popular in Earth Sciences

This 10 page Class Notes was uploaded by Cathrine Hoeger on Thursday October 29, 2015. The Class Notes belongs to ESCI 401 at University of New Hampshire taught by Staff in Fall. Since its upload, it has received 27 views. For similar materials see /class/231682/esci-401-university-of-new-hampshire in Earth Sciences at University of New Hampshire.

Similar to ESCI 401 at UNH

Popular in Earth Sciences


Reviews for The Dynamic Earth


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 10/29/15
CLASS 8 WEATHERING OF ROCKS AND MINERALS INTRODUCTION Weathering is the alteration or breakdown of rocks and minerals near or at the surface of the earth Weathering relates to changes of rock in place Erosion in contrast relates to removal of material In practice the distinction between weathering and erosion may become blurred but try to keep the concepts separate Weathering is very important in many ways It forms the soil we need to grow food on and has a big in uence on water chemistry It produces sedimentary particles and groundwater chemicals to cement them into sedimentary rock Weathering concentrates important mineral ores and even gives hints about where to nd them Weathering and erosion combine to sculpt landscapes and topography MECHANICAL WEATHERING This term refers to breakdown of rocks by such processes as splitting by expanding ice or growing roots Temperature changes cause rocks to expand contract and eventually split Rocks may expand and crack as overburden pressures are reduced by erosion Read about mechanical weathering in your text CHEMICAL WEATHERING Most minerals are subject to chemical or biochemical alteration at and near the surface of the earth Some minerals like halite and calcite simply dissolve to produce ions Others like feldspar alter to form completely new minerals How can we determine what changes occur during weathering How rapidly does weathering proceed What minerals are relatively stable slow to change and which ones are unstable weather rapidly HOW TO DETERMINE MINERAL AND ROCK STABILITY Laboratory experiments are one way to determine what chemical changes can occur and what the relative stabilities of minerals are We can heat minerals in water cook them in hot acids and colonize them with bacteria We can measure the changes that occur and how fast they proceed Although these tests can be precise and accurate we have to worry that nature is more complex than our experiments Maybe we ve omitted some key factor Another approach is to compare and contrast the degree of weathering on monuments of known age such as tombstones and buildings A potential difficulty is that external conditions may have changed since the monument was erected For example Egyptian obelisks had not weathered significantly for thousands of years before they were ripped off and taken to London and Paris In the damp dirty air of these northern cities weathering has been hundreds of times faster than in the clean dry air of the desert This method is limited by the short span of human culture compared to geologic ages Examination of natural outcrops tells us a lot about mineral stability We can study not only the weathered surface of an outcrop but can also examine the deep interior In this way we can determine the sequence of changes that have occurred during weathering A limitation is that we may have little evidence of the time scale of alteration A fourth approach is to note regular relationships between lithology rock type and topography form of the landscape Intuitively we suppose that rock at higher elevation is more resistant to weathering and erosion than rocks at lower elevations The main limitation here is that the higher rock might simply been higher initially not left behind as a result of weathering and erosion On the plus side we can apply this method to most ofthe earth s surface CHEMICAL STABILITY OF SILICATE MINERALS Application of stability tests of all kinds leads to the same conclusions the high temperature silicate minerals are less stable under normal climatic conditions than are the low temperature minerals Thus olivine and Ca plagioclase are the least stable whereas quartz and muscovite mica are the most stable The order of stability is just opposite to the order of crystallization from a silicate melt That is it s just the opposite of Bowen s reaction series In this context normal climate means a moist temperate one such as New Hampshire and we should be careful not to misapply these conclusions in other climates Thus in the equatorial jungles of South America quartz may be very susceptible to solution WEATHERING OF GRANITE Quartz and potassium feldspar are the main minerals of granite Other minerals include plagioclase feldspar micas and hornblende amphibole How do these minerals weather In our climate quartz is very stable it barely changes at all Thus the quartz in granite survives to form sand grains Orthoclase combines with water and carbon dioxide hydration to yield potassium and carbonate ions in solution silica in solution and akes of kaolinite a clay mineral This reaction is accompanied by an increase in volume so the rock is wedged apart by the growing kaolinite crystals Sodium plagioclase another common mineral in granite weathers in the same way except that sodium ions are liberated instead of potassium ones Because C02 is used up in these reactions they may act to limit the Greenhouse Effect global warming from excess C02 in the atmosphere As the atmosphere warms the weathering reactions go faster use up C02 and thus limit the extent of warming at least over long periods of time The weathering of hornblende is very complex so we ll look at an idealized pyroxene instead Pyroxene is not a common mineral of granite but we can use it as a proxy for important oxidation reactions Reaction of pyroxene with water and oxygen yields silica in solution plus an iron hydroxide goethite limonite that may remain as a yellow or brown stain on the weathering rock Lots of quartz grains in New Hampshire have a tan limonite stain as do many outcrops Biotite mica weathers somewhat as pyroxene does whereas muscovite mica is quite stable and persists in sediments as little akes WEATHERING OF PYRITE Pyrite FeSZ is a common ore mineral found in quartz veins with silver gold and other valuable materials It is also very common in coal Pyrite combines with water and oxygen to form iron hydroxide goethite limonite plus sulphuric acid When this reaction occurs in waste heaps outside mines it leaches acid into streams with devastating effect on plants and animals When coal is burned the reaction can occur in the atmosphere This leads in turn to acid rain with a host of negative consequences Oxidation of pyrite in waste heaps of quartz vein ores can also lead to acidification of streams On the plus side the location of ore veins may be aided by residual patches of oxidation products overlying the veins MWERAL STABLLATY FSB200 5 BOWEN S REACTONSERLES all melt a Soh cl 70 W v ohvine 100 I o I Ah 1 I mmxene 7 z 1 wmxte Z L i b39ioti te E 0 KL M artkochse amp L 39 muscovi ce E L f uavt3 w ZL phjiodcse 4 empe ram re 39 739me 39 FSB ZOOI most sEaHe least Ska H e 3139 BLT T E uuv t3 02 I Q o 1 i N e 4 mm hsmq plas ochsa TEE pyroxene 0ngth 30 303 I amphquot bo 1 13w Mumbfems swyaoncou 7395 Motlk E I 1 Km a M o OH I S orihoc lte 3 N M53308 39 I K Al 530 o muscwitz E kA2m 83 ounclo g We T ERN OF AN ua 3 SJ 0 Ovaaod39ak 2 k A 0 Hzcas 4 3 o 391 k 0 4 302 N2 3205 OHM fpswx a 9 4 Fem 03 01 H10 Kaohncke CHE fr 5 4 SZOZ 4 F OCO H3 goetkite imonWe kcoszoquot FSBIZOOI We THemNca OF 39PYRH EL 39 Fesz 0K53 h H r v L304 FQOCOHB Pjr 39t upnun c ad gotthike quot immi rt m E wag 43 2304 H1304 P V We Fag civmnbm H53 LVSQWEC39kQ H1304 bovnite Cos F 3q elfewb L3 pew r had He FcMq SB Sphinck g33 ramcash Fe 3 ckdcoc e C qu cobakktlze cm s ckaho pbrilce Cu Fest mok b zni e M03 F83 2001 H20 302 O quot9 H2304 H2804 Ca cogWax4 024420 Ca304 2 H20 Ca304 2 H20 1 ML jl lti 0 Ca C 03 Cc c iJce C CL 304 cme rL e 01304 2 H20 S PSum g F58J 200 e least staUe most S abe STA FHLATY or Smm39rE M N BALS of i N e MSfQZSR C34 P j f39oxevx e i mmFe Si 03 aum bo a M C02Cm5fe d 5 51908022 cu2 Mo bi ce a I Km a ms 0 0 yer302mg 2 Na m 33 08 K m 8303 muscovlte kA2H 33 nanny2 iuar39ts Si 02 p39a5quotocam Ce ZSL1 1 w V P 33b r i Aoti te39 r0 b dior gf h Bv39ani h Q


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Janice Dongeun University of Washington

"I used the money I made selling my notes & study guides to pay for spring break in Olympia, Washington...which was Sweet!"

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.