Gigaimages / virtual microscope


Very clayey Horizon

Is there any illuviation clay in this sample?

B Horizon. Thin section 11628.



Low/medium magnifications
Low/medium magnifications
High magnifications
High magnifications

Micromorphologic features

After browsing these images you should have found, at least, the following characteristics (image on the left with polarizer only and the one on the right with crossed nicols).

1 Clay coating with net boundaries over Fe nodule
2 Clay coating with fuzzy boundaries over Fe nodule
3 Clay coating in pore
4 Clay coating in pore
5 Clay coating in pore
6 Clay coating in pore
7 Clay coating in pore
8 Clay coating in pore
9 Clay coating in pore
11 Root       12 Soil pedotubule

Is there any illuviation clay in this sample?

According to the images with the crossed nicols (1 and 2), we could conclude there is illuviation clay. However, if we observe the images with polarizer only, we can see that the clay coatings are covering the nodules composed of Fe (likely hematites) instead of the walls of the pores. These clay orientations can be a consecuence of simple preassures due to humidity changes, what is usual in such a clayey horizon.

The coating of images 3, 4, 5, 6, 7 y 9 cover the walls of pores but do not really adapt to the pore's shape, they are not continous and the boundaries are fuzzy. Observing the images with one polarizer only, there is no different between the coating and the sourrounding clay. If it were illuvial clay, the traslocation could have chosen the particles, that is, the smaller clay, cleaner, more transparent and possibly with a different colour (from other horizon) and a clearer boundary (formed "on" the walls od pores not "in" the walls).

The crack of the image 8 shows crossed nicols and a clay coating with clear illuvial features. However, if we pay attention, we realise that is just a piece of the sand grain coating above. Additionally, with polarizer only we can not distiguish the coating clay from the clay of the soil surrounding it.

The clay orientations in image 10 are not limited to the coating of the nodule of Fe, but they are all aroung the soil matrix.

Acording to the previous discussion we think it could possibly be a Bw Horizon.


Soil data

The landscape

The profile

General features and classification

Macromorphologic features

Analytical data


This soil belongs to the topographical map 1025 Loja. Soil Map. Project LUCDEME. 1997.