1. ESPIRITU, GIAN CARLO R 2005-43251 SOIL 210
chronosequences
ESPIRITU, GIAN CARLO R
SOIL 210

2. dEFinition
 set of sites formed from the same parent material or substrate that differs in the time since they were formed
a sequence of related soils that differ, one from the other, in certain properties primarily as a result of time as a soil forming factor. (Jenny, 1994)
the best-documented chronosequences:
Studies of Mudflows in Northern California (Dickson and Crocker 1954); and
Terrace Sequence in Spain (Dorronsoro and Alonso 1994).
difficult to establish the age of soils
informative but is site specific

3. A CHRONOSEQUENCE OF SOILS AND VEGETATION NEAR MOUNT SHASTA, CALIFORNIA
Dickson and Crocker studied mudflows from 27 to an estimated 1200 years old.
Mean Annual Precipitation: 1200 mm, mostly in the winter
Mean Annual Temperature: 10oC
Flows are pulverized rocks of hornblende-andesite composition, coarse sand texture
Organic Carbon in the 60 year old flows are the same in the older flows
Total Organic Matter (OM) and Nitrogen (N) reached a maximum in 205 year flows
Bulk Density (BD) below 10 cm: decreased from 1.6 g/cc in the 27 year old flow through 1.4 g/cc for 60 and 205 year flows, to 1.2 g/cc for 566 and 1200 year flows
Clay content: 1% in 27 year flows to 4% in 60 year flows and remained constant

4. SOIL DEVELOPMENT INDICES OF SOILS DEVELOPED ON FLUVIAL TERRACES (PEÑARANDA DE BRACAMONTE, SALAMANCA, SPAIN)
Dorronsoro and Alonso in 1994 studied the relationship between the age and soil development index values in a fluvial sequence and their distribution with regards to profile depth.
Mean Annual Precipitation: 412 mm
Mean Annual Temperature: 11oC
The soils of this chronosequence show continuous changes in all properties analyzed without seeming to reach a steady state. However, development is very slow for the oldest soils.

5. Weathering
Hilger performed an experiment by exposing uniform rock particles mm in diameter to atmospheric influences for 17 years.
Percentage of original particles left at different time interval (x) and the amounts of fine earth (less than 0.5 mm in diameter) formed (y).
Limestone showed more resistance than sandstone.
Fig1. Hilger’s Experimental Weathering Series

6. Hilger’s experimental weathering series
K2O + Na2O
=ba1
SiO2
=sa
Al2O3
Al2O5
Type of Material
Absolute
Relative
Limestone
Rock
5.000
1.000
17.08
1.00
Fine earth
0.514
0.103
7.330
0.429
Mica Schist
0.418
5.880
0.288
0.690
4.870
0.829
Sandstone
0.247
40.10
0.275
1.111
23.90
0.596
Bissinger determined the chemical composition of Hilger’s series.
Differential weathering is clearly indicative
Limestone suffered great losses of K and Na than Sandstone.
The same relationship exists in leaching of silica
In all cases, Fine earth has a lower sa value than original rock which indicates addition of Aluminum
Sandstone is easily weathered physically but limestone easily weathers chemically
Table1. Chemical Data on Rock Weathering

7. Volcanic soils
1883 – tremendous volcanic eruption happened in Krakatao in the Sunda Strait between Java and Sumatra.
Lang-Eiland was covered with volcanic material over 100 ft or 30 m.
1928 – Ecoma Verestege collected soil samples from a soil profile
Surface Soil – 35 cm thick
Middle Layer – Pumice
Parent Rock – Pumice, 42 m thick
Mineral Examination – Van Baren
Surface layer – contained Anhydrite, Pyrite and Wollastonite which are considered new formations
Detailed Chemical Analysis – Möser
Indicates tropical weathering, N and OM are low

8. Volcanic soils Microbiological Population – Schuitemaker
Comparable with garden soil

9. Rock Middle Layer Surface Soil
Constituents
Rock
Middle Layer
Surface Soil
SiO2, percent
67.55
65.87
61.13
Al2O3, percent
15.19
16.31
17.24
Fe2O3, percent
1.52
1.74
2.56
FeO, percent
2.15
2.05
2.59
CaO, percent
2.89
3.07
3.61
Na2O, percent
4.47
4.01
3.90
K2O, percent
1.95
1.53
1.78
CO2, percent -
0.04
H2O, above 110o, percent
2.46
3.17
3.25
H2O, below 110o, percent
0.33
Organic Matter, %
0.45
Nitrogen, %
0.018
0.012
0.035 pH
5.3
5.8
6.0
Particles below 20μ, %
22.4
26.1
Color
White
Gray
SiO2:Al2O3=sa
7.56
6.86
6.03 β
0.816
0.776
Table8. Condensed Data of Lang-Eiland Soil, 45 Years Old
Annual Precipitation:
262 cm
Annual Temperature
27.8OC
HJenny, Factors of Soil Formation, 1994 Chapter 3, Effect of Time on Soil Formation

10. Moraines (glacial)
glacially formed accumulation of unconsolidated glacial debris