Index: DamEngine/trunk/xsd/DamStabilityParameters.xsd
===================================================================
diff -u -r5703 -r5720
--- DamEngine/trunk/xsd/DamStabilityParameters.xsd	(.../DamStabilityParameters.xsd)	(revision 5703)
+++ DamEngine/trunk/xsd/DamStabilityParameters.xsd	(.../DamStabilityParameters.xsd)	(revision 5720)
@@ -45,6 +45,7 @@
         <xs:restriction base="xs:int">
           <xs:enumeration value="OnBoundaryLines" />
           <xs:enumeration value="Specified" />
+          <xs:enumeration value="Automatic" />
         </xs:restriction>
       </xs:simpleType>
     </xs:attribute>
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreator.cs
===================================================================
diff -u -r5702 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreator.cs	(.../UpliftVanGridCreator.cs)	(revision 5702)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreator.cs	(.../UpliftVanGridCreator.cs)	(revision 5720)
@@ -40,7 +40,7 @@
         var upliftVanCalculationGrid = new UpliftVanCalculationGrid
         {
             IsGridsAutomatic = slipCircleDefinition.UpliftVanGridSizeDetermination == GridSizeDetermination.Automatic,
-            IsTangentLinesAutomatic = slipCircleDefinition.UpliftVanTangentLinesDefinition == TangentLinesDefinition.OnBoundaryLines,
+            TangentLinesCreationMethod = slipCircleDefinition.UpliftVanTangentLinesDefinition,
             RightGridXLeft = 0,
             RightGridXRight = 0,
             RightGridXCount = 0,
@@ -120,17 +120,11 @@
     public static void DetermineTangentLines(UpliftVanCalculationGrid upliftVanCalculationGrid, SlipCircleDefinition slipCircleDefinition,
                                              SoilProfile1D soilProfile1D)
     {
-        switch (slipCircleDefinition.UpliftVanTangentLinesDefinition)
+        upliftVanCalculationGrid.TangentLinesCreationMethod = slipCircleDefinition.UpliftVanTangentLinesDefinition;
+        if (slipCircleDefinition.UpliftVanTangentLinesDefinition == TangentLinesDefinition.Specified)
         {
-            case TangentLinesDefinition.OnBoundaryLines:
-                // In the Macrostability kernel, the automatic tangent lines are set to the boundaries, no need to do anything here.
-                upliftVanCalculationGrid.IsTangentLinesAutomatic = true;
-                break;
-            case TangentLinesDefinition.Specified:
-                upliftVanCalculationGrid.IsTangentLinesAutomatic = false;
-                DetermineTangentLinesSpecified(upliftVanCalculationGrid, soilProfile1D,
-                                               slipCircleDefinition.UpliftVanTangentLinesDistance);
-                break;
+            DetermineTangentLinesSpecified(upliftVanCalculationGrid, soilProfile1D,
+                                        slipCircleDefinition.UpliftVanTangentLinesDistance);
         }
     }
 
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillMacroStabilityWrapperInputFromEngine.cs
===================================================================
diff -u -r5702 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillMacroStabilityWrapperInputFromEngine.cs	(.../FillMacroStabilityWrapperInputFromEngine.cs)	(revision 5702)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillMacroStabilityWrapperInputFromEngine.cs	(.../FillMacroStabilityWrapperInputFromEngine.cs)	(revision 5720)
@@ -372,8 +372,10 @@
 
     private void TransferUpliftVanSearchAreaSettings(SearchAreaConditions kernelSearchAreaConditions)
     {
-        kernelSearchAreaConditions.AutoTangentLines = UpliftVanCalculationGrid.IsTangentLinesAutomatic;
+        kernelSearchAreaConditions.AutoTangentLines = UpliftVanCalculationGrid.TangentLinesCreationMethod is TangentLinesDefinition.Automatic or TangentLinesDefinition.OnBoundaryLines;
         kernelSearchAreaConditions.AutoSearchArea = UpliftVanCalculationGrid.IsGridsAutomatic;
+        kernelSearchAreaConditions.OnlyAbovePleistoceen = UpliftVanCalculationGrid.TangentLinesCreationMethod == TangentLinesDefinition.Automatic;
+        kernelSearchAreaConditions.MaxSpacingBetweenBoundaries = 0.8;
         kernelSearchAreaConditions.TangentLineNumber = UpliftVanCalculationGrid.TangentLineCount;
         kernelSearchAreaConditions.TangentLineZTop = UpliftVanCalculationGrid.TangentLineZTop;
         kernelSearchAreaConditions.TangentLineZBottom = UpliftVanCalculationGrid.TangentLineZBottom;
@@ -429,7 +431,7 @@
             GridZBottom = UpliftVanCalculationGrid.RightGridZBottom
         };
         
-        if (!UpliftVanCalculationGrid.IsTangentLinesAutomatic)
+        if (UpliftVanCalculationGrid.TangentLinesCreationMethod == TangentLinesDefinition.Specified)
         {
             kernelUpliftVanCalculationGrid.TangentLines = UpliftVanCalculationGrid.TangentLineLevels.ToArray();
         }
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreatorTests.cs
===================================================================
diff -u -r5702 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreatorTests.cs	(.../UpliftVanGridCreatorTests.cs)	(revision 5702)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityInwards/UpliftVanGridCreatorTests.cs	(.../UpliftVanGridCreatorTests.cs)	(revision 5720)
@@ -41,7 +41,7 @@
     public void GivenGridSpecified_WhenDetermineGridsFromSettings_ThenGridsAreAsExpected()
     {
         // Given
-        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true, true);
+        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true);
         SurfaceLine2 surfaceLine = FactoryForSurfaceLines.CreateSurfaceLineForTestingGrid(10.0, 80.0);
         // When
         UpliftVanCalculationGrid upliftVanCalculationGrid = UpliftVanGridCreator.DetermineGridsFromSettings(slipCircleDefinition, surfaceLine);
@@ -62,7 +62,7 @@
     public void GivenGridSpecifiedWithRightGridOverRightBoundary_WhenDetermineGridsFromSettings_ThenRightGridLimitedToRightBoundary()
     {
         // Given
-        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true, true);
+        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true);
         SurfaceLine2 surfaceLine = FactoryForSurfaceLines.CreateSurfaceLineForTestingGrid(10.0, 65.0);
         // When
         UpliftVanCalculationGrid upliftVanCalculationGrid = UpliftVanGridCreator.DetermineGridsFromSettings(slipCircleDefinition, surfaceLine);
@@ -80,7 +80,7 @@
     public void GivenGridSpecifiedWithUpliftPoint_WhenDetermineGridsFromSettings_ThenRightGridStartsAsExpected()
     {
         // Given
-        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true, true);
+        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true);
         slipCircleDefinition.XCoordinateLowestUpliftFactorPoint = 75.0;
         SurfaceLine2 surfaceLine = FactoryForSurfaceLines.CreateSurfaceLineForTestingGrid(10.0, 80.0);
         // When
@@ -102,7 +102,7 @@
     public void GivenGridAutomatic_WhenDetermineGridsFromSettings_ThenIsGridsAutomatic()
     {
         // Given
-        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(false, true);
+        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(false);
         SurfaceLine2 surfaceLine = FactoryForSurfaceLines.CreateSurfaceLineForTestingGrid(10.0, 80.0);
         // When
         UpliftVanCalculationGrid upliftVanCalculationGrid = UpliftVanGridCreator.DetermineGridsFromSettings(slipCircleDefinition, surfaceLine);
@@ -113,12 +113,13 @@
     }
     
     [Test]
-    [TestCase(true)]
-    [TestCase(false)]
-    public void GivenSlipCircleDefinitionAndSoilProfile1D_WhenDetermineTangentLines_ThenTangentLinesAreAsExpected(bool isTangentLinesSpecified)
+    [TestCase(TangentLinesDefinition.OnBoundaryLines)]
+    [TestCase(TangentLinesDefinition.Specified)]
+    [TestCase(TangentLinesDefinition.Automatic)]
+    public void GivenSlipCircleDefinitionAndSoilProfile1D_WhenDetermineTangentLines_ThenTangentLinesAreAsExpected(TangentLinesDefinition tangentLinesDefinition)
     {
         // Given
-        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true, isTangentLinesSpecified);
+        SlipCircleDefinition slipCircleDefinition = CreateSlipCircleDefinitionSpecified(true, tangentLinesDefinition);
         SoilProfile1D soilProfile1D = FactoryForSoilProfiles.CreateClaySandProfile(out _, surfaceLevelSoilProfile1D, bottomLayerSoilProfile1D);
         
         // When
@@ -127,7 +128,6 @@
         // Then
         Assert.Multiple(() =>
         {
-            Assert.That(upliftVanCalculationGrid.IsTangentLinesAutomatic, Is.Not.EqualTo(isTangentLinesSpecified));
             CheckValuesTangentLines(upliftVanCalculationGrid);
         });
     }
@@ -190,7 +190,7 @@
         var expectedZTop = 0.0;
         var expectedCount = 0;
 
-        if (!upliftVanCalculationGrid.IsTangentLinesAutomatic)
+        if (upliftVanCalculationGrid.TangentLinesCreationMethod == TangentLinesDefinition.Specified)
         {
             expectedZBottom = bottomLayerSoilProfile1D - specifiedTangentDistance;
             expectedCount = (int) Math.Round((surfaceLevelSoilProfile1D - expectedZBottom) / specifiedTangentDistance) + 1;
@@ -206,7 +206,7 @@
         });
     }
    
-    private static SlipCircleDefinition CreateSlipCircleDefinitionSpecified(bool isGridSpecified, bool isTangentLinesSpecified)
+    private static SlipCircleDefinition CreateSlipCircleDefinitionSpecified(bool isGridSpecified, TangentLinesDefinition tangentLinesDefinition = TangentLinesDefinition.Automatic)
     {
         var slipCircleDefinition = new SlipCircleDefinition
         {
@@ -219,7 +219,7 @@
             UpliftVanRightGridVerticalPointDistance = 2,
             UpliftVanRightGridHorizontalPointCount = 6,
             UpliftVanRightGridHorizontalPointDistance = 2,
-            UpliftVanTangentLinesDefinition = isTangentLinesSpecified ? TangentLinesDefinition.Specified: TangentLinesDefinition.OnBoundaryLines,
+            UpliftVanTangentLinesDefinition = tangentLinesDefinition,
             UpliftVanTangentLinesDistance = specifiedTangentDistance
         };
         return slipCircleDefinition;
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillEngineFromMacroStabilityWrapperInput.cs
===================================================================
diff -u -r5702 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillEngineFromMacroStabilityWrapperInput.cs	(.../FillEngineFromMacroStabilityWrapperInput.cs)	(revision 5702)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillEngineFromMacroStabilityWrapperInput.cs	(.../FillEngineFromMacroStabilityWrapperInput.cs)	(revision 5720)
@@ -178,7 +178,7 @@
 
         if (kernelSearchAreaConditions.AutoTangentLines)
         {
-            SlipCircleDefinition.UpliftVanTangentLinesDefinition = TangentLinesDefinition.OnBoundaryLines;
+            SlipCircleDefinition.UpliftVanTangentLinesDefinition = kernelSearchAreaConditions.OnlyAbovePleistoceen ? TangentLinesDefinition.Automatic : TangentLinesDefinition.OnBoundaryLines;
         }
         else
         {
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityInwards/MacroStabilityInwardsKernelWrapperTests.cs
===================================================================
diff -u -r5702 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityInwards/MacroStabilityInwardsKernelWrapperTests.cs	(.../MacroStabilityInwardsKernelWrapperTests.cs)	(revision 5702)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityInwards/MacroStabilityInwardsKernelWrapperTests.cs	(.../MacroStabilityInwardsKernelWrapperTests.cs)	(revision 5720)
@@ -501,16 +501,24 @@
         });
     }
 
+    /// <summary>
+    /// For a given search method and a given grid determination method, expected is that tangent lines Automatic give a lower
+    /// safety factor than On boundary lines because there are extra tangent lines.
+    /// </summary>
     [Test]
     [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Specified, TangentLinesDefinition.OnBoundaryLines, 1.2812, 4)]
-    [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Automatic, TangentLinesDefinition.OnBoundaryLines, 1.4752, 3)]
-    [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Specified, TangentLinesDefinition.OnBoundaryLines, 2.2763, 3)]
-    [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Automatic, TangentLinesDefinition.OnBoundaryLines, 1.1205, 926)]
+    [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Specified, TangentLinesDefinition.Automatic, 1.2360, 2)]
     [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Specified, TangentLinesDefinition.Specified, 0.4909, 24)]
+    [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Automatic, TangentLinesDefinition.OnBoundaryLines, 1.4752, 3)]
+    [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Automatic, TangentLinesDefinition.Automatic, 1.1437, 3)]
     [TestCase(MStabSearchMethod.Grid, GridSizeDetermination.Automatic, TangentLinesDefinition.Specified, 1.1475, 3)]
+    [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Specified, TangentLinesDefinition.OnBoundaryLines, 2.2763, 3)]
+    [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Specified, TangentLinesDefinition.Automatic, 2.0267, 3)]
     [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Specified, TangentLinesDefinition.Specified, 1.7680, 3)]
+    [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Automatic, TangentLinesDefinition.OnBoundaryLines, 1.1205, 926)]
+    [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Automatic, TangentLinesDefinition.Automatic, 1.1123, 800)]
     [TestCase(MStabSearchMethod.BeeSwarm, GridSizeDetermination.Automatic, TangentLinesDefinition.Specified, 1.1146, 826)]
-    public void TestFullCalculationSucceedsWithUpliftVan(MStabSearchMethod searchMethod, GridSizeDetermination gridSizeDetermination, TangentLinesDefinition tangentLinesDefinition, double expectedSafetyFactor, int expectedLogMessageCount)
+    public void GivenUpliftVanModel_WhenCalculatingWithDifferentSearchAreaSettings_ReturnsLogicalResults(MStabSearchMethod searchMethod, GridSizeDetermination gridSizeDetermination, TangentLinesDefinition tangentLinesDefinition, double expectedSafetyFactor, int expectedLogMessageCount)
     {
         // Prepare the wrapper. Result is input for the calculation dll
         DamKernelInput kernelInput = CreateDamKernelInputForTest(MStabModelType.UpliftVan, searchMethod, gridSizeDetermination, tangentLinesDefinition);
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/UpliftVanCalculationGrid.cs
===================================================================
diff -u -r4540 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/UpliftVanCalculationGrid.cs	(.../UpliftVanCalculationGrid.cs)	(revision 4540)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/UpliftVanCalculationGrid.cs	(.../UpliftVanCalculationGrid.cs)	(revision 5720)
@@ -20,6 +20,7 @@
 // All rights reserved.
 
 using System.Collections.Generic;
+using Deltares.DamEngine.Data.General;
 
 namespace Deltares.DamEngine.Calculators.KernelWrappers.MacroStabilityCommon;
 
@@ -77,13 +78,13 @@
     /// <summary>Gets or sets the right grid z count.</summary>
     /// <value>The right grid z count.</value>
     public int RightGridZCount { get; set; }
+    
+    /// <summary>Gets or sets the tangent line creation method: automatic, specified or on boundary lines.</summary>
+    /// <value>The tangent line creation setting .</value>
+    public TangentLinesDefinition TangentLinesCreationMethod { get; set; }
 
     /// <summary>Gets or sets the tangent line z top.</summary>
     /// <value>The tangent line z top.</value>
-    /// <summary>Gets or sets the tangent line creation automatic or specified.</summary>
-    /// <value>The tangent line creation setting .</value>
-    public bool IsTangentLinesAutomatic { get; set; }
-
     public double TangentLineZTop { get; set; }
 
     /// <summary>Gets or sets the tangent line z bottom.</summary>
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityCommon/MacroStabilityIoTests.cs
===================================================================
diff -u -r5702 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityCommon/MacroStabilityIoTests.cs	(.../MacroStabilityIoTests.cs)	(revision 5702)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityCommon/MacroStabilityIoTests.cs	(.../MacroStabilityIoTests.cs)	(revision 5720)
@@ -152,7 +152,7 @@
             RightGridZBottom = random.NextDouble(),
             RightGridXCount = random.Next(),
             RightGridZCount = random.Next(),
-            IsTangentLinesAutomatic = true,
+            TangentLinesCreationMethod = TangentLinesDefinition.OnBoundaryLines,
             TangentLineZBottom = 0,
             TangentLineZTop = 10,
             TangentLineCount = 10
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/General/StabilityEnumerations.cs
===================================================================
diff -u -r4540 -r5720
--- DamEngine/trunk/src/Deltares.DamEngine.Data/General/StabilityEnumerations.cs	(.../StabilityEnumerations.cs)	(revision 4540)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/General/StabilityEnumerations.cs	(.../StabilityEnumerations.cs)	(revision 5720)
@@ -22,7 +22,7 @@
 namespace Deltares.DamEngine.Data.General;
 
 /// <summary>
-/// Types of (calculation) models for Stability. 
+/// Types of (calculation) model. 
 /// </summary>
 public enum MStabModelType
 {
@@ -41,7 +41,7 @@
 }
 
 /// <summary>
-/// Types of Intrusion Vertical Water Pressures
+/// Types of intrusion vertical water pressure.
 /// </summary>
 public enum IntrusionVerticalWaterPressureType
 {
@@ -53,7 +53,7 @@
 }
 
 /// <summary>
-/// Types of MStab Shear Strength models
+/// Types of shear strength model.
 /// </summary>
 public enum MStabShearStrength
 {
@@ -66,7 +66,7 @@
 }
 
 /// <summary>
-/// Types of MStab Search Methods
+/// Types of search method.
 /// </summary>
 public enum MStabSearchMethod
 {
@@ -76,7 +76,7 @@
 }
 
 /// <summary>
-/// Types of MStab Grid Positions
+/// Types of grid position.
 /// </summary>
 public enum MStabGridPosition
 {
@@ -85,7 +85,7 @@
 }
 
 /// <summary>
-/// Types of MStab Zones
+/// Types of zone.
 /// </summary>
 public enum MStabZonesType
 {
@@ -94,16 +94,17 @@
 }
 
 /// <summary>
-/// Types of tangent lines definitions.
+/// Types of tangent lines definition.
 /// </summary>
 public enum TangentLinesDefinition
 {
     OnBoundaryLines = 0,
-    Specified = 1
+    Specified = 1,
+    Automatic = 2
 }
 
 /// <summary>
-/// Types of GridSize Determinations
+/// Types of grid size determination.
 /// </summary>
 public enum GridSizeDetermination
 {