Chapter 8. Weathering, Soils and Mass Movement BFRB Pages 157 - 161. Weathering and Erosion. Weathering - Def . - the break down of rocks that have been exposed to the atmosphere.
Weathering, Soils and
BFRB Pages 157 - 161
Remember the Rock Cycle Diagram? Page 6 of the “Handy Dandy” ESRT’s…
Chemical weathering Dandy” ESRT’s…– rocks break down as their minerals change in chemical composition (they become different substances).
Physical weathering– rocks are broken down into smaller pieces without changing their chemical composition (what they’re made of).
AKA - mechanical weathering2 Types of Weathering
Mt. Brewster – looks solid, right? Dandy” ESRT’s…
Close up shows jagged rocks from FROST wedging! Dandy” ESRT’s…
This boulder has been split apart by frost action!!! Dandy” ESRT’s…
Rock weathered by a rockfall
Rock weathered by a stream
Vertical Exfoliation very differently!
Link to visualization
Lichen – light green/looks like bread mold
Moss – dark green
You see, it all comes together!!!
Oxidative weathering of mineral deposits (new deposits are white/yellow, weathered deposits are reddish-brown)
“Gnarled Rock” – a formation of limestone chemically weathered by acid rain
Pitted limestone from rainfall weathered by acid rain
Carbonic acid weathered by acid rain in groundwater causes caves to form.
When the acidic groundwater comes in contact with limestone, the limestone dissolves and caves and caverns are formed.
Howe Caverns in NY and Carlsbad Caverns in NM are examples of these beautiful geologic formations
Stalactites weathered by acid rain
Carlsbad Caverns – New Mexico
The central area of rock was weathered by acid rainless resistant to weathering…thus the “arch” was formed! This is differential weathering.
Devil’s Tower, Wyoming - An igneous intrusion (volcanic neck – the underneath of the volcano) surrounded by less resistant sedimentary rock layers. Erosion has exposed this monolith! This is an example of differential weathering!!!
You may recognize it if you’ve ever seen “Close Encounters of the Third Kind”
Devil’s Marbles, Australia – Mechanical weathering from wind and sand!
Water runoff seeps into the soil at the base of granite rock faces. Over time, water and permanently moist soil conditions act together to chemically weather away granite minerals such as feldspar and mica!
Parthenon – Athens, Greece
Soil has 4 components:
PARENT MATERIAL is the rock that the soil forms from
VIF - MUCH OF THE SOIL IN NYS IS TRANSPORTED SOIL LEFT BEHIND BY GLACIERS!
Cross section of soil layers neck – the underneath of the volcano) surrounded by
Each layer is called a HORIZON
Horizon O/A = Topsoil (mostly humus, some weathered rock)
Horizon B = Mostly weathered rock, some organic material (mineral rich zone)
Horizon C = Broken Bedrock
HORIZON A neck – the underneath of the volcano) surrounded by
MOVEMENTS OF SOIL, ROCK, AND LOOSE MATERIALS CAUSED BY THE FORCE OF GRAVITY
Even though rapid mass movement is more noticeable than slow mass movement, overall, more material is transported via creep than all others combined – because it is occurring in many more places and all the time!!!!