4 POROSITY – the percentage of open pore space between rock particles (sediment) Big spaces, not a lot of themLittle spaces, but lots of themExample: conglomerateExample: sandstone
5 Recalling the recent Porosity and Permeability lab, make your hypothesis. How do you predict the relationship between porosity and permeability? IOW, does porosity affect permeability?____________
6 Which size held the most water? Demo #11st trial:look at red yellow greenonlyPorosity - Amount of open space between sedimentsDemo #1Which size held the most water?
7 Big spaces, not a lot of them LESS surface area Little spaces but lots of themGREATER surface areaEQUALPOROSITYIMPORTANT TO REMEMBERThe size of the rock particle DOES NOT change the porosity!
8 Porosity is determined by Porosity - The amount of open space in between rock particles.Porosity is determined by1. Shape - Well rounded particles have greater porosity than angular particles.ROUNDANGULARPOROSITYROUNDNESS
9 2. PACKING- The more closely packed the particles are, the lower the porosity.POROSITYPACKINGUNPACKEDPACKED
10 - If all particles are the same size, they are sorted. 3. SORTING-- If all particles are the same size, they are sorted.- If the particles are different sizes, they areunsorted (poorly sorted)- The more sorted the particles, the higher the porosityPOROSITYSORTING
11 does NOT affect porosity!!!!! (Shape, Packing, Sorting does) Particle Size alonedoes NOT affect porosity!!!!! (Shape, Packing, Sorting does)The porosity is the same for sorted particles, but not for unsorted particles.
20 CAPILLARITY – the process of water adhering to rock particles (cohesion) in small spaces, resulting in an UPWARD movement of the water through rock sediment.
21 The height water will rise in a small cylinder (capillary tube) so it is dependent on the diameter of the tube.
22 The effect of capillarity in soil pores can be seen between the glass beads above. Water was added to the beads when they were in contact, then the beads were separated. The water is adhering (sticking) to the beads, but cohesion keeps a strand of water between the beads. This is how water moves up a capillarity tube by water molecules attaching to each other.
23 Porosity does not depend on grain size HOWEVER… A quick review Remember!Porosity does not depend on grain size HOWEVER…As particle size permeabilityAs particle size capillarity
24 POORLY-SORTED PARTICLES: unsorted, mixed sizes (not in layers)WELL-SORTED PARTICLES: same size (in layers)
26 USING WHAT YOU LEARNED FROM VIEWING THE ABOVE SLIDES ANSWER THE FOLLOWING 10 QUESTION QUIZ ON THE INDEX CARD PROVIDED BY YOUR TEACHER. 1. Put your name on the top of the lined side of the index card. 2. Number each question. 3. Skip a line in between each question. 4. Turn in Quiz by next class!
27 The diagrams below represent three containers, A, B, and C, which were filled with equal volumes of uniformly sorted plastic beads. Water was poured into each container to determine porosity and infiltration time.1. Which data table best represents the porosity and infiltration time of the beads in containers A, B, C?ABD
28 2. Soil composed of which particle size usually has the greatest capillarity? A) fine sand C) silt B) pebbles D) coarse sand
29 3. When rainfall occurs, the rainwater will most likely become surface runoff if the land surface is impermeable C) sandyB) nearly flat D) covered with grass
30 A) silt and pebbles, only B) sand, pebbles, and the mixture, only A student performed a laboratory activity in which water was poured slowly into four cups containing equal volumes of loosely packed sediment samples, as shown in the diagram below. All particles were spherical in shape and uniform in size within the container. After the water level reached the surface of each sample, the student determined the amount of water that had been added.4. The results of the activity should have indicated that approximately equal amounts of water were added to the cups ofA) silt and pebbles, onlyB) sand, pebbles, and the mixture, onlyC) pebbles and the mixture, only
31 5. Which graph shows the effect of soil permeability on the amount of runoff in an area?
32 6. The diagrams below represent four permeable sediment samples 6. The diagrams below represent four permeable sediment samples. The sediments are composed of the same material, but differ in particle size and sorting. Which sediment sample will most likely have the fastest groundwater infiltration rate? And why?
33 7. What size rock particle can be transported by a stream moving at a velocity of 100 cm/s? A) fine sandB) pebblesC) siltD) coarse sand
34 8. The climate of Phoenix, NY, located in the northeastern part of the continent, ranges from warm and wet in the summer months to cold and snowy in the winter. What type of weathering do we experience according to the below climate graph?A) yellow--strong chemicalB) green--moderate chemicalwith frost actionC) blue--slight physicalD) purple—strong physical
35 9. If the amount of precipitation for an area was 125 cm/yr 9. If the amount of precipitation for an area was 125 cm/yr. and the average yearly temperature was 5oC, what type of weathering would be experienced in this region?A) moderate chemicalB) strong chemicalC) Very slightD) Moderate chemicalwith frost action
36 10 questions 10 pts. each 10. FOLLOW THE BELOW INSTRUCTIONS EXACTLY. If your last name begins with letter A – M, answer the following question:QUESTION: If the porosity of a material decreases, how will the permeability be affected? (increases, decreases, or stay the same)If your last name begins with the letter N – Z, answer this question:QUESTION: Which of the following materials would have greater permeability?A) a gravel pitB) a sandy beachC) a muddy fieldD) an asphalt parking lot10 questions10 pts. each