diff --git a/R/RcppExports.R b/R/RcppExports.R
index ffb204a..d5530d2 100644
--- a/R/RcppExports.R
+++ b/R/RcppExports.R
@@ -29,6 +29,10 @@ rcpp_cast_sf <- function(sf, cast_to, close = TRUE) {
     .Call(`_sfheaders_rcpp_cast_sf`, sf, cast_to, close)
 }
 
+rcpp_interleave <- function(sfc) {
+    .Call(`_sfheaders_rcpp_interleave`, sfc)
+}
+
 rcpp_fill_list <- function(v, line_ids) {
     .Call(`_sfheaders_rcpp_fill_list`, v, line_ids)
 }
diff --git a/inst/include/sfheaders/df/sfc.hpp b/inst/include/sfheaders/df/sfc.hpp
index 0b348c3..27fdccd 100644
--- a/inst/include/sfheaders/df/sfc.hpp
+++ b/inst/include/sfheaders/df/sfc.hpp
@@ -293,9 +293,6 @@ namespace df {
         columns[ M_COLUMN ] = true;
       }
 
-      // Rcpp::Rcout << "dim: " << dim << std::endl;
-      // Rcpp::Rcout << "columns: " << columns << std::endl;
-
       sfg_class = cls[1];
       sfg_type = get_sfg_type( sfg_class );
       sfg_column_idx = get_sfg_column_index( sfg_class );
@@ -355,9 +352,6 @@ namespace df {
     R_xlen_t i;
 
     std::string dim;
-
-    // TODO: change this
-    // needs to be dependant on 'dim'
     Rcpp::StringVector col_names = {"sfg_id","point_id","x","y","z","m"};
 
     Rcpp::NumericVector x( total_coordinates, Rcpp::NumericVector::get_na() );
diff --git a/inst/include/sfheaders/interleave/interleave.hpp b/inst/include/sfheaders/interleave/interleave.hpp
new file mode 100644
index 0000000..e635ae1
--- /dev/null
+++ b/inst/include/sfheaders/interleave/interleave.hpp
@@ -0,0 +1,78 @@
+#ifndef R_SFHEADERS_INTERLEAVE_H
+#define R_SFHEADERS_INTERLEAVE_H
+
+#include "sfheaders/df/sfc.hpp"
+#include <Rcpp.h>
+
+namespace sfheaders {
+namespace interleave {
+
+  template < int RTYPE >
+  inline SEXP interleave( Rcpp::Matrix< RTYPE >& mat ) {
+    R_xlen_t n_col = mat.ncol();
+    R_xlen_t n_row = mat.nrow();
+    Rcpp::Vector< RTYPE > res( n_col * n_row );
+    R_xlen_t i, j;
+    for( i = 0; i < n_row; ++i ) {
+      for( j = 0; j < n_col; ++j ) {
+        res[ j ] = mat( i, j );
+      }
+    }
+    return res;
+  }
+
+  inline SEXP interleave( Rcpp::List& lst) {
+    R_xlen_t i;
+    R_xlen_t n = lst.length();
+
+
+    Rcpp::NumericMatrix sfc_coordinates = sfheaders::df::sfc_n_coordinates( lst );
+    R_xlen_t n_geometries = sfc_coordinates.nrow();
+    R_xlen_t total_coordinates = sfc_coordinates( n_geometries - 1 , 1 );
+    total_coordinates = total_coordinates + 1;
+
+    //Rcpp::Rcout << "sfc_coordinates: " << sfc_coordinates << std::endl;
+
+    for( i = 0; i < n; ++i ) {
+      //SEXP sfg = sfc[ i ];
+
+    }
+    return Rcpp::List::create();
+  }
+
+  inline SEXP interleave( SEXP& sfg ) {
+    switch( TYPEOF ( sfg ) ) {
+    case INTSXP: {
+    if( Rf_isMatrix( sfg ) ) {
+      Rcpp::IntegerMatrix im = Rcpp::as< Rcpp::IntegerMatrix >( sfg );
+      return interleave( im );
+    } else {
+      return sfg; // it's already a vector
+    }
+    }
+    case REALSXP: {
+    if( Rf_isMatrix( sfg ) ) {
+      Rcpp::NumericMatrix im = Rcpp::as< Rcpp::NumericMatrix >( sfg );
+      return interleave( im );
+    } else {
+      return sfg; // it's already a vector
+    }
+    }
+    case VECSXP: {
+    if( Rf_isNewList( sfg ) ) {
+      Rcpp::List lst = Rcpp::as< Rcpp::List >( sfg );
+      return interleave( lst );
+    }
+    }
+    default: {
+      Rcpp::stop("sfheaders - can not interleave this type of object");
+    }
+    }
+    return Rcpp::List::create();
+  }
+
+} // interleave
+} // sfheaders
+
+
+#endif
diff --git a/src/RcppExports.cpp b/src/RcppExports.cpp
index 8f92730..4662c9c 100644
--- a/src/RcppExports.cpp
+++ b/src/RcppExports.cpp
@@ -90,6 +90,17 @@ BEGIN_RCPP
     return rcpp_result_gen;
 END_RCPP
 }
+// rcpp_interleave
+SEXP rcpp_interleave(Rcpp::List sfc);
+RcppExport SEXP _sfheaders_rcpp_interleave(SEXP sfcSEXP) {
+BEGIN_RCPP
+    Rcpp::RObject rcpp_result_gen;
+    Rcpp::RNGScope rcpp_rngScope_gen;
+    Rcpp::traits::input_parameter< Rcpp::List >::type sfc(sfcSEXP);
+    rcpp_result_gen = Rcpp::wrap(rcpp_interleave(sfc));
+    return rcpp_result_gen;
+END_RCPP
+}
 // rcpp_fill_list
 Rcpp::List rcpp_fill_list(Rcpp::NumericVector v, Rcpp::IntegerMatrix line_ids);
 RcppExport SEXP _sfheaders_rcpp_fill_list(SEXP vSEXP, SEXP line_idsSEXP) {
@@ -834,6 +845,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"_sfheaders_rcpp_count_new_sfc_objects", (DL_FUNC) &_sfheaders_rcpp_count_new_sfc_objects, 2},
     {"_sfheaders_rcpp_cast_sfc", (DL_FUNC) &_sfheaders_rcpp_cast_sfc, 3},
     {"_sfheaders_rcpp_cast_sf", (DL_FUNC) &_sfheaders_rcpp_cast_sf, 3},
+    {"_sfheaders_rcpp_interleave", (DL_FUNC) &_sfheaders_rcpp_interleave, 1},
     {"_sfheaders_rcpp_fill_list", (DL_FUNC) &_sfheaders_rcpp_fill_list, 2},
     {"_sfheaders_rcpp_list_sizes", (DL_FUNC) &_sfheaders_rcpp_list_sizes, 1},
     {"_sfheaders_rcpp_list_type", (DL_FUNC) &_sfheaders_rcpp_list_type, 1},
diff --git a/src/interleave.cpp b/src/interleave.cpp
new file mode 100644
index 0000000..08bd2ad
--- /dev/null
+++ b/src/interleave.cpp
@@ -0,0 +1,70 @@
+#include <Rcpp.h>
+#include "sfheaders/df/sfc.hpp"
+#include "sfheaders/interleave/interleave.hpp"
+
+
+void interleave_geometry(SEXP& sfg, Rcpp::NumericVector& res, R_xlen_t& coordinate_counter ) {
+
+}
+
+// [[Rcpp::export]]
+SEXP rcpp_interleave( Rcpp::List sfc ) {
+
+  // the input will be a long data.frame
+  // or an sf object
+  // if it's a data.frame, it needs id columns and geometry columns
+  // can probably do this one later?
+  // and focus on the 'sf', because it doesn't need any extra headers / thought / logic
+
+  //Rcpp::NumericMatrix sfc_coordinates = sfheaders::df::sfc_n_coordinates( sfc );
+
+  //return sfc_coordinates;
+
+  // the STRIDE depends on the dimension being the same for every pair of coordinates
+
+
+  Rcpp::CharacterVector cls;
+  std::string dim_expected;
+  std::string dim;
+
+  R_xlen_t n = sfc.length();
+  R_xlen_t i;
+  Rcpp::IntegerVector n_coordinates( n );
+  R_xlen_t sfg_count = 0;   // move outside loop so it's cumulative
+  for( i = 0; i < n; ++i ) {
+    SEXP sfg = sfc[ i ];
+
+    cls = sfheaders::utils::getSfgClass( sfg );
+    if( i == 0 ) {
+      dim_expected = cls[0];
+    } else {
+      dim = cls[0];
+      if ( dim != dim_expected ) {
+        Rcpp::stop("sfheaders - interleaving only works when all geometries have the same dimension (XY(Z(M)))");
+      }
+    }
+
+    n_coordinates[ i ] = sfg_count;
+    sfheaders::df::sfg_n_coordinates( sfg, sfg_count );
+  }
+  // the last iteration gives the total number of coordinates
+  // which will be the length of the vector (* stride (dim) );
+  Rcpp::Rcout << "total coordinates: " << sfg_count << std::endl;
+
+  int stride = ( dim_expected == "XYZ" || dim_expected == "XYM" ? 3 : ( dim_expected == "XYZM" ? 4 : 2 )  );
+  R_xlen_t total_coordinates = sfg_count * stride;
+  Rcpp::NumericVector res( total_coordinates );
+  R_xlen_t coordinate_counter = 0;
+  // now fill this vector with all the coorinates from the coordinates
+  for( i = 0; i < n; ++i ) {
+    SEXP sfg = sfc[ i ];
+     // depending on the GEOMETRY
+     // get each coordinate
+     // do I iterate each row?
+     SEXP temp = sfheaders::interleave::interleave( sfg );
+  }
+
+  return res;
+}
+
+