diff --git a/R/seriesExtent.R b/R/seriesExtent.R
index 270efeff..8f2193b4 100644
--- a/R/seriesExtent.R
+++ b/R/seriesExtent.R
@@ -3,9 +3,10 @@
 #' @description This function downloads a generalized representations of a soil series extent from SoilWeb, derived from the current SSURGO snapshot. Data can be returned as vector outlines (`sf` object) or gridded representation of area proportion falling within 800m cells (`SpatRaster` object). Gridded series extent data are only available in CONUS. Vector representations are returned with a GCS/WGS84 coordinate reference system and raster representations are returned with an Albers Equal Area / NAD83 coordinate reference system (`EPSG:5070`).
 #' 
 #' @param s a soil series name, case-insensitive
-#' @param type series extent representation, 'vector': results in an `sf` object and 'raster' results in a `SpatRaster` object
+#' @param type series extent representation, `'vector'`: results in an `sf` object and `'raster'` results in a `SpatRaster` object
 #' @param timeout time that we are willing to wait for a response, in seconds
-#' 
+#' @param as_Spatial Return sp (`SpatialPolygonsDataFrame`) / raster (`RasterLayer`) classes? Default: `FALSE`.
+#' @return An R spatial object, class depending on `type` and `as_Spatial` arguments
 #' @references \url{https://casoilresource.lawr.ucdavis.edu/see/}
 #' @author D.E. Beaudette
 #' 
@@ -49,10 +50,8 @@
 #' }
 #' }
 #' 
-seriesExtent <- function(s, type = c('vector', 'raster'), timeout = 60) {
-
-  if (!requireNamespace("curl")) 
-    stop("package curl is required to download series extent data", call. = FALSE)
+seriesExtent <- function(s, type = c('vector', 'raster'), timeout = 60, 
+                         as_Spatial = getOption('soilDB.return_Spatial', default = FALSE)) {
   
   # download timeout should be longer than default (13 seconds) 
   h <- .soilDB_curl_handle(timeout = timeout)
@@ -67,15 +66,15 @@ seriesExtent <- function(s, type = c('vector', 'raster'), timeout = 60) {
   # ch: this is a shared curl handle with options set
   res <- switch(
     type,
-    vector = {.vector_extent(s, ch = h)},
-    raster = {.raster_extent(s, ch = h)}
+    vector = {.vector_extent(s, ch = h, as_Spatial = as_Spatial)},
+    raster = {.raster_extent(s, ch = h, as_Spatial = as_Spatial)}
   )
   
   return(res)
 }
 
 # 2022-08-15: converted from download.file() -> curl::curl_download() due to SSL errors
-.vector_extent <- function(s, ch) {
+.vector_extent <- function(s, ch, as_Spatial) {
   
   if (!requireNamespace("sf")) 
     stop("package sf is required to return vector series extent grids", call. = FALSE)
@@ -109,12 +108,16 @@ seriesExtent <- function(s, type = c('vector', 'raster'), timeout = 60) {
   # reset row names in attribute data to series name
   rownames(x) <- as.character(x$series)
   
+  if (as_Spatial) {
+    x <- sf::as_Spatial(x)
+  }
+  
   # GCS WGS84
   return(x)
 }
 
 # 2022-08-15: converted from download.file() -> curl::curl_download() due to SSL errors
-.raster_extent <- function(s, ch) {
+.raster_extent <- function(s, ch, as_Spatial) {
   
   if (!requireNamespace("terra")) 
     stop("package terra is required to return raster series extent grids", call. = FALSE)
@@ -157,6 +160,14 @@ seriesExtent <- function(s, type = c('vector', 'raster'), timeout = 60) {
   # make CRS explicit
   terra::crs(x) <- 'EPSG:5070'
   
+  if (as_Spatial) {
+    if (requireNamespace("raster", quietly = TRUE)) {
+      x <- raster::raster(x) 
+    } else {
+      stop("Package `raster` is required to return raster data as a RasterLayer object with soilDB.return_Spatial=TRUE")
+    }
+  }
+  
   return(x)
 }
 
diff --git a/R/taxaExtent.R b/R/taxaExtent.R
index c2d62ff5..2c341946 100644
--- a/R/taxaExtent.R
+++ b/R/taxaExtent.R
@@ -5,13 +5,15 @@
 #' 
 #' @param x single taxon label (e.g. `haploxeralfs`) or formative element (e.g. `pale`), case-insensitive
 #' 
-#' @param level the taxonomic level within the top 4 tiers of Soil Taxonomy, one of \code{c('order', 'suborder', 'greatgroup', 'subgroup')}
+#' @param level the taxonomic level within the top 4 tiers of Soil Taxonomy, one of `'order'`, `'suborder'`, `'greatgroup'`, `'subgroup'`
 #' 
 #' @param formativeElement logical, search using formative elements instead of taxon label
 #' 
 #' @param timeout time that we are willing to wait for a response, in seconds
 #' 
-#' @return a `SpatRaster` object
+#' @param as_Spatial Return raster (`RasterLayer`) classes? Default: `FALSE`.
+#' 
+#' @return a `SpatRaster` object (or `RasterLayer` when `as_Spatial=TRUE`)
 #' 
 #' @author D.E. Beaudette and A.G. Brown
 #' 
@@ -19,12 +21,12 @@
 #' 
 #' ## Taxon Queries
 #' 
-#' Taxon labels can be conveniently extracted from the "ST_unique_list" sample data, provided by the [SoilTaxonomy package](https://github.com/ncss-tech/SoilTaxonomy).
+#' Taxon labels can be conveniently extracted from the `"ST_unique_list"` sample data, provided by the [SoilTaxonomy package](https://github.com/ncss-tech/SoilTaxonomy).
 #' 
 #' ## Formative Element Queries
 #' 
 #' ### Greatgroup:
-#' The following labels are used to access taxa containing the following formative elements (in parenthesis).
+#' The following labels are used to access taxa containing the following formative elements (in parentheses)
 #' 
 #' * acr: (acro/acr) extreme weathering
 #' * alb: (alb) presence of an albic horizon
@@ -201,7 +203,9 @@
 #' 
 #' }
 #' @export
-taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup'), formativeElement = FALSE, timeout = 60) {
+taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup'),
+                       formativeElement = FALSE, timeout = 60,
+                       as_Spatial = getOption('soilDB.return_Spatial', default = FALSE)) {
  
   ## sanity checks
   
@@ -213,10 +217,10 @@ taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup
   
   # main branch
   # formative element query
-  if(formativeElement) {
+  if (formativeElement) {
     
     # formative elements are only available at the greatgroup / subgroup for now
-    if(level %in% c('order', 'suborder')) {
+    if (level %in% c('order', 'suborder')) {
       stop('formative element queries are only supported for greatgroup and subgroup taxa', call. = FALSE)
     }
     
@@ -240,8 +244,8 @@ taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup
   } else {
     # taxon query
     
-    # encode taxa name: spaces -> underscores
-    x <- gsub(pattern=' ', replacement='_', x = tolower(x), fixed = TRUE)
+    # encode taxon name: spaces -> underscores
+    x <- gsub(pattern = ' ', replacement = '_', x = tolower(x), fixed = TRUE)
     
     # convert taxa level to path
     subdir <- switch(
@@ -264,8 +268,6 @@ taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup
     
   }
   
-  
-  
   # init temp files
   tf <- tempfile(fileext = '.tif')
   
@@ -280,7 +282,7 @@ taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup
   )
   
   # trap errors
-  if(inherits(res, 'error')){
+  if (inherits(res, 'error')) {
     message('no data returned')
     return(NULL)
   }
@@ -296,11 +298,19 @@ taxaExtent <- function(x, level = c('order', 'suborder', 'greatgroup', 'subgroup
   
   # transfer layer name
   # conversion of '_' -> ' ' only meaningful in taxon query
-  names(r) <- gsub(pattern='_', replacement=' ', x = x, fixed = TRUE)
+  names(r) <- gsub(pattern = '_', replacement = ' ', x = x, fixed = TRUE)
   
   # make CRS explicit
   terra::crs(r) <- 'EPSG:5070'
   
+  if (as_Spatial) {
+    if (requireNamespace("raster", quietly = TRUE)) {
+      r <- raster::raster(r) 
+    } else {
+      stop("Package `raster` is required to return raster data as a RasterLayer object with as_Spatial=TRUE")
+    }
+  }
+  
   return(r)
   
 }
diff --git a/man/seriesExtent.Rd b/man/seriesExtent.Rd
index baa13f20..a01a18a7 100644
--- a/man/seriesExtent.Rd
+++ b/man/seriesExtent.Rd
@@ -4,14 +4,24 @@
 \alias{seriesExtent}
 \title{Retrieve Soil Series Extent Maps from SoilWeb}
 \usage{
-seriesExtent(s, type = c("vector", "raster"), timeout = 60)
+seriesExtent(
+  s,
+  type = c("vector", "raster"),
+  timeout = 60,
+  as_Spatial = getOption("soilDB.return_Spatial", default = FALSE)
+)
 }
 \arguments{
 \item{s}{a soil series name, case-insensitive}
 
-\item{type}{series extent representation, 'vector': results in an \code{sf} object and 'raster' results in a \code{SpatRaster} object}
+\item{type}{series extent representation, \code{'vector'}: results in an \code{sf} object and \code{'raster'} results in a \code{SpatRaster} object}
 
 \item{timeout}{time that we are willing to wait for a response, in seconds}
+
+\item{as_Spatial}{Return sp (\code{SpatialPolygonsDataFrame}) / raster (\code{RasterLayer}) classes? Default: \code{FALSE}.}
+}
+\value{
+An R spatial object, class depending on \code{type} and \code{as_Spatial} arguments
 }
 \description{
 This function downloads a generalized representations of a soil series extent from SoilWeb, derived from the current SSURGO snapshot. Data can be returned as vector outlines (\code{sf} object) or gridded representation of area proportion falling within 800m cells (\code{SpatRaster} object). Gridded series extent data are only available in CONUS. Vector representations are returned with a GCS/WGS84 coordinate reference system and raster representations are returned with an Albers Equal Area / NAD83 coordinate reference system (\code{EPSG:5070}).
diff --git a/man/taxaExtent.Rd b/man/taxaExtent.Rd
index 765be8e8..80c97f0f 100644
--- a/man/taxaExtent.Rd
+++ b/man/taxaExtent.Rd
@@ -8,20 +8,23 @@ taxaExtent(
   x,
   level = c("order", "suborder", "greatgroup", "subgroup"),
   formativeElement = FALSE,
-  timeout = 60
+  timeout = 60,
+  as_Spatial = getOption("soilDB.return_Spatial", default = FALSE)
 )
 }
 \arguments{
 \item{x}{single taxon label (e.g. \code{haploxeralfs}) or formative element (e.g. \code{pale}), case-insensitive}
 
-\item{level}{the taxonomic level within the top 4 tiers of Soil Taxonomy, one of \code{c('order', 'suborder', 'greatgroup', 'subgroup')}}
+\item{level}{the taxonomic level within the top 4 tiers of Soil Taxonomy, one of \code{'order'}, \code{'suborder'}, \code{'greatgroup'}, \code{'subgroup'}}
 
 \item{formativeElement}{logical, search using formative elements instead of taxon label}
 
 \item{timeout}{time that we are willing to wait for a response, in seconds}
+
+\item{as_Spatial}{Return raster (\code{RasterLayer}) classes? Default: \code{FALSE}.}
 }
 \value{
-a \code{SpatRaster} object
+a \code{SpatRaster} object (or \code{RasterLayer} when \code{as_Spatial=TRUE})
 }
 \description{
 This function downloads a generalized representation of the geographic extent of any single taxon from the top 4 levels of Soil Taxonomy, or taxa matching a given formative element used in Great Group or subgroup taxa. Data are provided by SoilWeb, ultimately sourced from the current SSURGO snapshot. Data are returned as \code{raster} objects representing area proportion falling within 800m cells. Currently area proportions are based on major components only. Data are only available in CONUS and returned using an Albers Equal Area / NAD83(2011) coordinate reference system (EPSG: 5070).
@@ -30,13 +33,13 @@ This function downloads a generalized representation of the geographic extent of
 See the \href{https://ncss-tech.github.io/AQP/soilDB/taxa-extent.html}{Geographic Extent of Soil Taxa} tutorial for more detailed examples.
 \subsection{Taxon Queries}{
 
-Taxon labels can be conveniently extracted from the "ST_unique_list" sample data, provided by the \href{https://github.com/ncss-tech/SoilTaxonomy}{SoilTaxonomy package}.
+Taxon labels can be conveniently extracted from the \code{"ST_unique_list"} sample data, provided by the \href{https://github.com/ncss-tech/SoilTaxonomy}{SoilTaxonomy package}.
 }
 
 \subsection{Formative Element Queries}{
 \subsection{Greatgroup:}{
 
-The following labels are used to access taxa containing the following formative elements (in parenthesis).
+The following labels are used to access taxa containing the following formative elements (in parentheses)
 \itemize{
 \item acr: (acro/acr) extreme weathering
 \item alb: (alb) presence of an albic horizon