Surface weathering produces coatings of mineral materials which may be similar to

or quite different from

the minerals of the underlying parent rock.There coating are usuallyonly microns to millimeters in thickness

but they completely control the reflectance spectra control the terrain. In a similar way coatings formed from adherence of wind-borne dusts

cemented or not

will also dominate the reflectance spectra as seen in remotely sensed ima gery. cemented coatings are often dark-colored （even black） and are usually termed "desert varnish" from their common occurrence in arid regions. Despite their featureless

dark colorto our eyes

there coatings （often days）

show characteristic reflectance minima in the shortwave infrared （SWIR） regions

by which their mineralogical composition can be deduced.Thus to relate remotely sensed imagery to actual ground "geology"requires a good knowledge of the surficial character of the exposed rock outcrops.It is not always possible to find"fresh" surfaces in the field

and one must always differentiate"upper-surface"spectra（andalso "lower-surface" spectra）from the spectra of the "inner rock"materials.This paper describes one of the major surface coatings which is on the weathered dolomite carbonate from the early Poleozoic sequences of easternmost California USA.