diff --git a/x-pack/plugins/maps/common/descriptor_types/index.ts b/x-pack/plugins/maps/common/descriptor_types/index.ts
index b0ae065856a5..fb47344ab32d 100644
--- a/x-pack/plugins/maps/common/descriptor_types/index.ts
+++ b/x-pack/plugins/maps/common/descriptor_types/index.ts
@@ -5,6 +5,7 @@
  */
 
 export * from './data_request_descriptor_types';
-export * from './sources';
+export * from './source_descriptor_types';
+export * from './layer_descriptor_types';
 export * from './map_descriptor';
 export * from './style_property_descriptor_types';
diff --git a/x-pack/plugins/maps/common/descriptor_types/layer_descriptor_types.ts b/x-pack/plugins/maps/common/descriptor_types/layer_descriptor_types.ts
new file mode 100644
index 000000000000..a04d0e1a978f
--- /dev/null
+++ b/x-pack/plugins/maps/common/descriptor_types/layer_descriptor_types.ts
@@ -0,0 +1,73 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+/* eslint-disable @typescript-eslint/consistent-type-definitions */
+
+import { Query } from 'src/plugins/data/public';
+import { StyleDescriptor, VectorStyleDescriptor } from './style_property_descriptor_types';
+import { DataRequestDescriptor } from './data_request_descriptor_types';
+import { AbstractSourceDescriptor, ESTermSourceDescriptor } from './source_descriptor_types';
+
+export type JoinDescriptor = {
+  leftField?: string;
+  right: ESTermSourceDescriptor;
+};
+
+export type LayerDescriptor = {
+  __dataRequests?: DataRequestDescriptor[];
+  __isInErrorState?: boolean;
+  __isPreviewLayer?: boolean;
+  __errorMessage?: string;
+  __trackedLayerDescriptor?: LayerDescriptor;
+  alpha?: number;
+  id: string;
+  joins?: JoinDescriptor[];
+  label?: string | null;
+  areLabelsOnTop?: boolean;
+  minZoom?: number;
+  maxZoom?: number;
+  sourceDescriptor: AbstractSourceDescriptor | null;
+  type?: string;
+  visible?: boolean;
+  style?: StyleDescriptor | null;
+  query?: Query;
+};
+
+export type VectorLayerDescriptor = LayerDescriptor & {
+  style: VectorStyleDescriptor;
+};
+
+export type RangeFieldMeta = {
+  min: number;
+  max: number;
+  delta: number;
+  isMinOutsideStdRange?: boolean;
+  isMaxOutsideStdRange?: boolean;
+};
+
+export type Category = {
+  key: string;
+  count: number;
+};
+
+export type CategoryFieldMeta = {
+  categories: Category[];
+};
+
+export type GeometryTypes = {
+  isPointsOnly: boolean;
+  isLinesOnly: boolean;
+  isPolygonsOnly: boolean;
+};
+
+export type StyleMetaDescriptor = {
+  geometryTypes?: GeometryTypes;
+  fieldMeta: {
+    [key: string]: {
+      range: RangeFieldMeta;
+      categories: CategoryFieldMeta;
+    };
+  };
+};
diff --git a/x-pack/plugins/maps/common/descriptor_types/sources.ts b/x-pack/plugins/maps/common/descriptor_types/source_descriptor_types.ts
similarity index 65%
rename from x-pack/plugins/maps/common/descriptor_types/sources.ts
rename to x-pack/plugins/maps/common/descriptor_types/source_descriptor_types.ts
index 6e8884d942e1..400b6a41ead7 100644
--- a/x-pack/plugins/maps/common/descriptor_types/sources.ts
+++ b/x-pack/plugins/maps/common/descriptor_types/source_descriptor_types.ts
@@ -15,8 +15,6 @@ import {
   SCALING_TYPES,
   MVT_FIELD_TYPE,
 } from '../constants';
-import { StyleDescriptor, VectorStyleDescriptor } from './style_property_descriptor_types';
-import { DataRequestDescriptor } from './data_request_descriptor_types';
 
 export type AttributionDescriptor = {
   attributionText?: string;
@@ -136,83 +134,3 @@ export type GeojsonFileSourceDescriptor = {
   name: string;
   type: string;
 };
-
-export type JoinDescriptor = {
-  leftField?: string;
-  right: ESTermSourceDescriptor;
-};
-
-// todo : this union type is incompatible with dynamic extensibility of sources.
-// Reconsider using SourceDescriptor in type signatures for top-level classes
-export type SourceDescriptor =
-  | AbstractSourceDescriptor
-  | XYZTMSSourceDescriptor
-  | WMSSourceDescriptor
-  | KibanaTilemapSourceDescriptor
-  | KibanaRegionmapSourceDescriptor
-  | ESTermSourceDescriptor
-  | ESSearchSourceDescriptor
-  | ESGeoGridSourceDescriptor
-  | EMSFileSourceDescriptor
-  | ESPewPewSourceDescriptor
-  | TiledSingleLayerVectorSourceDescriptor
-  | EMSTMSSourceDescriptor
-  | EMSFileSourceDescriptor
-  | GeojsonFileSourceDescriptor;
-
-export type LayerDescriptor = {
-  __dataRequests?: DataRequestDescriptor[];
-  __isInErrorState?: boolean;
-  __isPreviewLayer?: boolean;
-  __errorMessage?: string;
-  __trackedLayerDescriptor?: LayerDescriptor;
-  alpha?: number;
-  id: string;
-  joins?: JoinDescriptor[];
-  label?: string | null;
-  areLabelsOnTop?: boolean;
-  minZoom?: number;
-  maxZoom?: number;
-  sourceDescriptor: SourceDescriptor | null;
-  type?: string;
-  visible?: boolean;
-  style?: StyleDescriptor | null;
-  query?: Query;
-};
-
-export type VectorLayerDescriptor = LayerDescriptor & {
-  style?: VectorStyleDescriptor;
-};
-
-export type RangeFieldMeta = {
-  min: number;
-  max: number;
-  delta: number;
-  isMinOutsideStdRange?: boolean;
-  isMaxOutsideStdRange?: boolean;
-};
-
-export type Category = {
-  key: string;
-  count: number;
-};
-
-export type CategoryFieldMeta = {
-  categories: Category[];
-};
-
-export type GeometryTypes = {
-  isPointsOnly: boolean;
-  isLinesOnly: boolean;
-  isPolygonsOnly: boolean;
-};
-
-export type StyleMetaDescriptor = {
-  geometryTypes?: GeometryTypes;
-  fieldMeta: {
-    [key: string]: {
-      range: RangeFieldMeta;
-      categories: CategoryFieldMeta;
-    };
-  };
-};
diff --git a/x-pack/plugins/maps/public/classes/sources/source.ts b/x-pack/plugins/maps/public/classes/sources/source.ts
index 696c07376575..4a050cc3d7d1 100644
--- a/x-pack/plugins/maps/public/classes/sources/source.ts
+++ b/x-pack/plugins/maps/public/classes/sources/source.ts
@@ -11,9 +11,9 @@ import { ReactElement } from 'react';
 import { Adapters } from 'src/plugins/inspector/public';
 import { copyPersistentState } from '../../reducers/util';
 
-import { SourceDescriptor } from '../../../common/descriptor_types';
 import { IField } from '../fields/field';
 import { MAX_ZOOM, MIN_ZOOM } from '../../../common/constants';
+import { AbstractSourceDescriptor } from '../../../common/descriptor_types';
 import { OnSourceChangeArgs } from '../../connected_components/layer_panel/view';
 
 export type SourceEditorArgs = {
@@ -56,7 +56,7 @@ export interface ISource {
   supportsFitToBounds(): Promise<boolean>;
   showJoinEditor(): boolean;
   getJoinsDisabledReason(): string | null;
-  cloneDescriptor(): SourceDescriptor;
+  cloneDescriptor(): AbstractSourceDescriptor;
   getFieldNames(): string[];
   getApplyGlobalQuery(): boolean;
   getIndexPatternIds(): string[];
@@ -70,17 +70,17 @@ export interface ISource {
 }
 
 export class AbstractSource implements ISource {
-  readonly _descriptor: SourceDescriptor;
+  readonly _descriptor: AbstractSourceDescriptor;
   readonly _inspectorAdapters?: Adapters | undefined;
 
-  constructor(descriptor: SourceDescriptor, inspectorAdapters?: Adapters) {
+  constructor(descriptor: AbstractSourceDescriptor, inspectorAdapters?: Adapters) {
     this._descriptor = descriptor;
     this._inspectorAdapters = inspectorAdapters;
   }
 
   destroy(): void {}
 
-  cloneDescriptor(): SourceDescriptor {
+  cloneDescriptor(): AbstractSourceDescriptor {
     return copyPersistentState(this._descriptor);
   }
 
@@ -133,7 +133,7 @@ export class AbstractSource implements ISource {
   }
 
   getApplyGlobalQuery(): boolean {
-    return 'applyGlobalQuery' in this._descriptor ? !!this._descriptor.applyGlobalQuery : false;
+    return !!this._descriptor.applyGlobalQuery;
   }
 
   getIndexPatternIds(): string[] {
diff --git a/x-pack/plugins/maps/server/maps_telemetry/maps_telemetry.ts b/x-pack/plugins/maps/server/maps_telemetry/maps_telemetry.ts
index f0286d7e5811..8688bbe549f5 100644
--- a/x-pack/plugins/maps/server/maps_telemetry/maps_telemetry.ts
+++ b/x-pack/plugins/maps/server/maps_telemetry/maps_telemetry.ts
@@ -23,7 +23,6 @@ import {
   ESGeoGridSourceDescriptor,
   ESSearchSourceDescriptor,
   LayerDescriptor,
-  SourceDescriptor,
 } from '../../common/descriptor_types';
 import { MapSavedObject } from '../../common/map_saved_object_type';
 // @ts-ignore
@@ -154,7 +153,7 @@ function isGeoShapeAggLayer(indexPatterns: IIndexPattern[], layer: LayerDescript
     return false;
   }
 
-  const sourceDescriptor: SourceDescriptor = layer.sourceDescriptor;
+  const sourceDescriptor = layer.sourceDescriptor;
   if (sourceDescriptor.type === SOURCE_TYPES.ES_GEO_GRID) {
     return isFieldGeoShape(
       indexPatterns,