public ShapeDescription( 
   GeometryType geometryType,
   SpatialReference spatialReference
)

{
  // Must be called within QueuedTask.Run
  void CreateFeatureClassSnippet(Geodatabase geodatabase, FeatureClass existingFeatureClass,
    SpatialReference spatialReference)
  {
    // Create a Cities feature class with the following fields
    // GlobalID
    // ObjectID
    // Name (string)
    // Population (integer)

    // This helper routine creates a FieldDescription for a GlobalID field with default values
    FieldDescription globalIDFieldDescription = FieldDescription.CreateGlobalIDField();

    // This helper routine creates a FieldDescription for an ObjectID field with default values
    FieldDescription objectIDFieldDescription = FieldDescription.CreateObjectIDField();

    // This helper routine creates a FieldDescription for a string field
    FieldDescription nameFieldDescription = FieldDescription.CreateStringField("Name", 255);

    // This helper routine creates a FieldDescription for an integer field
    FieldDescription populationFieldDescription = FieldDescription.CreateIntegerField("Population");

    // Assemble a list of all of our field descriptions
    List<FieldDescription> fieldDescriptions = new List<FieldDescription>()
        { globalIDFieldDescription, objectIDFieldDescription, nameFieldDescription, populationFieldDescription };

    // Create a ShapeDescription object
    ShapeDescription shapeDescription = new ShapeDescription(GeometryType.Point, spatialReference);

    // Alternatively, ShapeDescriptions can be created from another feature class.  In this case, the new feature class will inherit the same shape properties of the existing class
    ShapeDescription alternativeShapeDescription = new ShapeDescription(existingFeatureClass.GetDefinition());

    // Enable support for measure (M) value, if needed
    // shapeDescription.HasM = true;

    // Enable support for the vertical coordinate system (Z), if needed
    // shapeDescription.HasZ = true;

    // Create a FeatureClassDescription object to describe the feature class to create
    FeatureClassDescription featureClassDescription =
      new FeatureClassDescription("Cities", fieldDescriptions, shapeDescription);

    // Create a SchemaBuilder object
    SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

    // Add the creation of the Cities feature class to our list of DDL tasks
    schemaBuilder.Create(featureClassDescription);

    // Execute the DDL
    bool success = schemaBuilder.Build();

    // Inspect error messages
    if (!success)
    {
      IReadOnlyList<string> errorMessages = schemaBuilder.ErrorMessages;
      //etc.
    }
  }
}