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

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

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

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.

Weathering Hilger performed an experiment by exposing uniform rock particles 10-20 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

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

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

Volcanic soils Microbiological Population – Schuitemaker Comparable with garden soil

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

Moraines (glacial) glacially formed accumulation of unconsolidated glacial debris