Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SoilProfile2DSurfaceLineHelper.cs
===================================================================
diff -u -r6557 -r6572
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SoilProfile2DSurfaceLineHelper.cs	(.../SoilProfile2DSurfaceLineHelper.cs)	(revision 6557)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geotechnics/SoilProfile2DSurfaceLineHelper.cs	(.../SoilProfile2DSurfaceLineHelper.cs)	(revision 6572)
@@ -99,14 +99,19 @@
         var oldSurfaces = new List<SoilLayer2D>();
         oldSurfaces.AddRange(soilProfile2D.Surfaces);
 //GeometryExporter.ExportToFile(soilProfile2D.Geometry, GeometryExporter.VisualizationFolder + "_oldSurf_" +"GeometryStart.txt");
-//GeometryExporter.ExportWithSurfaceLineToJsonFile(GeometryExporter.VisualizationFolder + GeometryExporter.ExportJasonFile, clonedProfile.Geometry, surfaceLine);
-        var result = new SoilProfile2D();
-        result.Name = soilProfile2D.Name;
-        result.Geometry = CreateNewGeometryForSoilProfile2DByCombiningItsGeometryWithSurfaceLine(clonedSurfaceLine, clonedProfile.Geometry); 
-//GeometryExporter.ExportWithSurfaceLineToJsonFile(GeometryExporter.VisualizationFolder + GeometryExporter.ExportJasonFile, result.Geometry, surfaceLine);
+//GeometryExporter.ExportWithSurfaceLineToJsonFile(GeometryExporter.VisualizationFolder + GeometryExporter.ExportJasonFile, 
+//                                                 clonedProfile.Geometry, surfaceLine);
+        var result = new SoilProfile2D
+        {
+            Name = soilProfile2D.Name,
+            Geometry = CreateNewGeometryForSoilProfile2DByCombiningItsGeometryWithSurfaceLine(clonedSurfaceLine, 
+                                                                                              clonedProfile.Geometry)
+        }; 
+//GeometryExporter.ExportWithSurfaceLineToJsonFile(GeometryExporter.VisualizationFolder + GeometryExporter.ExportJasonFile,
+//                                                 result.Geometry, surfaceLine);
         RemoveGeometryDataOfSoilProfileAboveSurfaceLine(clonedSurfaceLine, ref result); 
 //GeometryExporter.ExportWithSurfaceLineToJsonFile(GeometryExporter.VisualizationFolder + GeometryExporter.ExportJasonFile, result.Geometry, surfaceLine);        
-        ReconstructSurfaces(ref result, clonedSurfaceLine, oldSurfaces, defaultSoil);
+        ReconstructSurfaces(ref result, clonedProfile.Geometry.Left, clonedProfile.Geometry.Right, oldSurfaces, defaultSoil);
 //GeometryExporter.ExportWithSurfaceLineToJsonFile(GeometryExporter.VisualizationFolder + GeometryExporter.ExportJasonFile, result.Geometry, surfaceLine);        
         ReconstructPreConsolidations(ref result, clonedProfile);
         result.Geometry.Rebox();
@@ -341,7 +346,7 @@
         result.DeleteLoosePoints();
     }
 
-    private static void ReconstructSurfaces(ref SoilProfile2D result, GeometryPointString surfaceLine,
+    private static void ReconstructSurfaces(ref SoilProfile2D result, double oldLeftLimit, double oldRightLimit, 
                                             List<SoilLayer2D> oldSurfaces, Soil defaultSoil)
     {
         result.Surfaces.Clear();
@@ -352,7 +357,7 @@
                 GeometrySurface = surface,
                 Soil = defaultSoil
             };
-            
+             
             SoilLayer2D layerFromOldSurfaces = SoilProfile2D.DetermineOriginalLayerFromOldSurfaces(surface, oldSurfaces);
             if (layerFromOldSurfaces != null && layerFromOldSurfaces.Soil != null)
             {
@@ -363,7 +368,8 @@
 
             if (layerFromOldSurfaces == null)
             {
-                SoilLayer2D oldLayer = DetermineLayerIfSurfaceIsLeftOrRightOfOldSurfaces(surface, oldSurfaces);
+                SoilLayer2D oldLayer = DetermineLayerIfSurfaceIsLeftOrRightOfOldSurfaces(surface, oldSurfaces, oldLeftLimit, 
+                                                                                         oldRightLimit);
                 
                 if (oldLayer != null)
                 {
@@ -393,35 +399,51 @@
     }
 
     private static SoilLayer2D DetermineLayerIfSurfaceIsLeftOrRightOfOldSurfaces(GeometrySurface surface, 
-                                                                                 List<SoilLayer2D> oldSurfaces)
+        List<SoilLayer2D> oldSurfaces, double oldLeftLimit, double oldRightLimit)
     {
         Point2D point = surface.DetermineValidTestPointBasedOnNewSurface();
+        // Check if the new surface is left or right of the old surfaces, if not just return null.
         if (!SoilProfile2D.IsSurfaceLeftOrRightOfOldSurfaces(point, oldSurfaces))
         {
             return null;       
         }
-            
-        double[] xMin = surface.OuterLoop.Points.Select(p => p.X).OrderBy(x => x).Distinct().ToArray();
-        double[] zMin = surface.OuterLoop.Points.Select(p => p.Z).OrderBy(z => z).Distinct().ToArray();
-        var leftPoint = new Point2D
-        {
-            X = xMin[0] - 0.1,
-            Z = zMin[0] + 0.1
-        };
 
-        SoilLayer2D soilLayer = SoilProfile2D.DetermineOldSurfaceFromTestPoint(oldSurfaces, leftPoint);
-        if (soilLayer != null)
+        SoilLayer2D soilLayer = null;
+        // Check if first two left points of the new surface have identical x values (they are vertical).
+        // If so, check these points are on the right boundary of the original geometry (so before extending)
+        // Then this surface is extended to the right side of the geometry and only then use material to its left.
+        Point2D[] leftPoints = surface.OuterLoop.Points.Select(p => p).OrderBy(x => x).ToArray();
+        Point2D leftPoint = leftPoints.First();
+        Point2D secondLeftPoint = leftPoints.Skip(1).First();
+        if (leftPoint.X.IsNearEqual(oldRightLimit) && leftPoint.X.IsNearEqual(secondLeftPoint.X))
         {
-            return soilLayer;
+            var newLeftPoint = new Point2D
+            {
+                X = leftPoint.X - 0.1,
+                Z = (leftPoint.Z + secondLeftPoint.Z) * 0.5
+            };
+            soilLayer = SoilProfile2D.DetermineOldSurfaceFromTestPoint(oldSurfaces, newLeftPoint);
+            if (soilLayer != null)
+            {
+                return soilLayer;
+            }
         }
-
-        var rightPoint = new Point2D
+        
+        // Check if first two right points of the new surface have identical x values (they are vertical).
+        // If so, check these points are on the left boundary of the original geometry (so before extending)
+        // Then this surface is extended to the left side of the geometry and only then use material to its right. 
+        Point2D rightPoint = leftPoints.Last();
+        Point2D secondRightPoint = leftPoints.Skip(leftPoints.Length - 2).First();
+        if (rightPoint.X.IsNearEqual(oldLeftLimit) && rightPoint.X.IsNearEqual(secondRightPoint.X))
         {
-            X = xMin[^1] + 0.1,
-            Z = zMin[0] + 0.1
-        };
+            var newRightPoint = new Point2D
+            {
+                X = rightPoint.X + 0.1,
+                Z = (rightPoint.Z + secondRightPoint.Z) * 0.5
+            };
+            soilLayer = SoilProfile2D.DetermineOldSurfaceFromTestPoint(oldSurfaces, newRightPoint);
+        }
 
-        soilLayer = SoilProfile2D.DetermineOldSurfaceFromTestPoint(oldSurfaces, rightPoint);
         return soilLayer;
     }