Distinction between textures and meaning of colours
Distinction between textures is currently only foreseen for alluvial deposits. The general guideline states that the distinction between textures should also be applied to aeolic, lacustrine, palustrine and emerged marine (eg. deltic, beach, tidal plain) deposits.
If preferred, it is possible not to distinguish between textures for lacustrine, palustrine and deltic deposits, using the generic symbol described in the Quaderno, serie III, n. 2.
The textures are as follows: gravel, sand, silt /loam, clay and peat. The polymodal granulometric distributions must be represented by the combination of elementary symbols (no longer two).
For glacial deposits the symbology described in Quaderno, serie III, n. 2 and subsequent additions is valid.
In ordert to make the maps easier to understand and read, the area symbol’s colour will be the same as the one used for the deposit origin.
The base colours (taken from the SGN chromatic manual) are as follows:
- slope deposits caused by gravity — red (PANTONE WARM RED)
- fluvial, fluvioglacial and slope deposits caused by scouring — blue (PANTONE REFLEX BLUE)
- glacial deposits — violet (PANTONE VIOLET)
- marine deposits (emerged and submerged) — light blue (PANTONE PROCESS BLUE)
- lacustrine-palustrine deposits — green (PANTONE GREEN)
- aeolic deposits — bistre (PANTONE 1395)
- deposits of anthropic origin – grey (PANTONE COOL GRAY 10 or NERO)
The travertine will continue to be identified by the horizontal blue pattern (PANTONE REFLEX BLUE)
It should be pointed out that the coordinated use of patterns for textures and colours used for the origin makes it possible to identify those deposits for which no specific symbol is foreseen. For example, a loess will be represented with a bistre (aeolic) silt texture, while a fluvial-lacustrine delta deposit will be identified by a green (lacustrine) sand and/or gravel texture. Specific descriptions in the legend will make it possible to describe the deposit in detail.
The use of area symbols to identify the type of deposit and the texture (when forseen) should be applied in case of legends organised according to UBSU (the criteria that should be followed, as reiterated above), given that a synthemic unit, characterised by a single base colour, can contain several types of deposit. The application of area symbols is not indispensable in the following cases:
- when the synthemic unit is characterised by homogeneous lithological deposits (eg. a synthem formed exclusively by fluvial gravel);
- when the synthemic unit is completely divided into lithostratigraphic units of different hierarchical ranks, each with its own colour. The same obviously applies if only lithostratigraphic units are used rather than UBSUs (although this should be avoided, especially for sheets where mapping is still underway).
In the case of legends organised according to the lithostratigraphic criterion, deposits of the same type (eg. slope deposits) but with different ages are to be represented using the same area symbol applied over the corresponding colour fields.
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