#' @name grain
#' @title Artificial raster dataset representing grain sizes
#' @description The ratified raster dataset represents grain sizes with the
#'   three classes clay, silt and sand, and WGS84 as a coordinate reference
#'   system.
#' @docType data
#' @keywords datasets raster
#' @importClassesFrom raster RasterLayer
#' 
#' @examples 
#' if (requireNamespace("raster", quietly = TRUE)) {
#'   library(raster)
#'   data(grain)
#'   grain
#' }
"grain"
