Table A1. S2 stratigraphic sequence (from bottom to top; cf. Fig. 4)	
Layer	Elevation*
(m)	Relative Elevation
(m)	Thickness†
(m)	Morphology‡	Relative
Albedo§	Composition¶	Description	SM(a)	
St1	1111-1124	0-13	22	Trough	Dark-Toned	Ice + 15% dust		L1	
St2	1124-1124	13-13	13	Ridge	Light-Toned	Ice + 5% dust			
St3	1124-1158	13-47	13	Trough	Dark-Toned	Ice + 15% dust			
St4	1158-1204	47-93	12	Ridge	Light-Toned	Ice + 5% dust			
St4bis	1204-1204	93-93	19	Trough	Dark-Toned	Ice + 15% dust			
St5	1204-1218	93-107	17	Ridge	Light-Toned	Ice + 5% dust			
St6	1218-1220	107-109	12	Trough	Dark-Toned	Ice + 15% dust			
St7	1220-1285	109-174	17	Trough	Light-Toned	Ice + 10% dust	Multilayer:
~10 layers of metrical thickness		
St8	1285-1326	174-215	28	Ridge	Light-Toned	CO2	LyP1	L2	
St9	1326-1326	215-215	15	Ridge	Light-Toned	CO2 or Ice+ 10% dust		L3	
St10	1326-1358	215-247	14	Trough	Dark-Toned	Ice + 15% dust		L4	
St11	1358-1358	247-247	18	Ridge	Light-Toned	Ice + 5% dust			
St12	1358-1358	247-247	12	Trough	Dark-Toned	Ice + 15% dust			
St13	1358-1358	247-247	21	Ridge	Light-Toned	Ice + 5% dust			
St14	1358-1406	247-295	23	Ridge	Light-Toned	Ice + 10% dust	Multilayer:
~6 layers of metrical thickness		
St15	1406-1429	295-318	22	Ridge	Light-Toned	Ice + 5% dust			
St16	1429-1445	318-334	24	Trough	Dark-Toned	CO2 or Ice+ 10% dust		L5	
St17	1445-1482	334-371	32	Ridge	Light-Toned	CO2	LyD2	L6	
St18	1482-1507	371-396	23	Trough	Dark-Toned	CO2 or Ice+ 10% dust	Drag Folds	L7	
St19	1507-1546	396-435	20	Ridge	Light-Toned	Ice + 5% dust	Drag Folds	L8	
St20	1546-1555	435-444	20	Trough	Dark-Toned	Ice + 15% dust	Drag Folds		
St21	1555-1577	444-466	16	Ridge	Light-Toned	Ice + 5% dust	Drag Folds		
St22	1577-1588	466-477	14	Trough	Dark-Toned	Ice + 15% dust	Drag Folds		
St23	1588-1611	477-500	22	Ridge	Light-Toned	Ice + 5% dust	Drag Folds		
St24	1611-1620	500-509	16	Trough	Dark-Toned	Ice + 15% dust	Drag Folds		
St25	1620-1631	509-520	21	Ridge	Light-Toned	Ice + 5% dust	Drag Folds		
St26	1631-1641	520-530	18	Trough	Dark-Toned	Ice + 15% dust	Drag Folds		
St27	1641-1671	530-560	41	Ridge	Light-Toned	Ice + 5% dust	Drag Folds		
St28	1671-1688	560-577	12	Trough	Dark-Toned	Ice + 15% dust	Drag Folds		
St29	1688-1688	577-577	9	Ridge	Light-Toned	Ice + 5% dust	Drag Folds		
St30	1688-1702	577-591	25	Trough	Dark-Toned	Ice + 10% dust	Drag Folds
Multilayer:
~7 layers of metrical thickness		
St31	1702-1733	591-622	30	Ridge	Light-Toned	Ice + 5% dust			
St32	1733-1733	622-622	13	Trough	Dark-Toned	CO2 or Ice+ 10% dust		L9	
St33	1733-1770	622-659	14	Ridge	Light-Toned	CO2	LyB3	L10	
St34	1770-1770	659-659	14	Trough	Dark-Toned	CO2 or Ice+ 10% dust		L11	
St35	1770-1770	659-659	13	Ridge	Light-Toned	Ice + 5% dust			
St36	1770-1790	659-679	15	Trough	Dark-Toned	CO2 or Ice+ 10% dust		L12	
St37	1790-1811	679-700	17	Ridge	Light-Toned	CO2	LyB3	L13	
St38	1811-1831	700-720	22	Trough	Dark-Toned	CO2		L14	
St39	1831-1856	720-745	18	Ridge	Light-Toned	Ice + 5% dust			
St40	1856-1862	745-751	26	Trough	Dark-Toned	CO2	Multilayer:
~5 layers of metrical thickness	L15	
St41	1862-1876	751-765	18	Ridge	Light-Toned	CO2	LyB3	L16	
St42	1876-1884	765-773	21	Trough	Dark-Toned	CO2 or Ice+ 10% dust	Multilayer:
~7 layers of metrical thickness	L17	
St43	1884-1895	773-784	31	Ridge	Light-Toned	CO2	LyB3	L18	
St44	1895-1911	784-800	5	Trough	Dark-Toned	CO2 or Ice+ 10% dust	
	
L19

St45	1911-1917	800-806	6	Ridge	Light-Toned	CO2 or Ice+ 10% dust		L20	
St46	1917-1932	806-821	8	Trough	Dark-Toned	CO2	LyB3	L21	
St47	1932-1936	821-825	6	Ridge	Light-Toned	CO2 or Ice+ 10% dust		L22	
St48	1936-1948	825-837	9	Trough	Dark-Toned	Ice + 15% dust		L23	
St49	1948-1948	837-837	2-5	Bench	Light-Toned	Ice + 10% dust			
St50	1948-1973	837-862	2-5	Bench	Light-Toned	Ice + 10% dust			
St51	1973-1973	862-862	2-5	Bench	Light-Toned	Ice + 10% dust			
St52	1973-1984	862-873	2-5	Bench	Light-Toned	Ice + 10% dust		L23	
St53	1984-1988	873-877	2-5	Bench	Light-Toned	Ice + 10% dust			
St54	1988-1988	877-877	4	Ridge	Light-Toned	Ice + 10% dust			
St55	1988-2002	877-891	6	Trough	Dark-Toned	Ice + 15% dust			
St56	2002-2037	891-926	8	Ridge	Medium-Toned	Ice + 10% dust			
St57	2037-2046	926-935	6	Trough	Medium-Toned	Ice + 10% dust			
St58	2046-2065	935-954	5-10	Bench	Medium-Toned	Ice + 10% dust			
St59	2065-2081	954-970	5-10	Bench	Medium-Toned	Ice + 10% dust			
St60	2081-2094	970-983	5-10	Bench	Medium-Toned	Ice + 10% dust			
St61	2094-2121	983-1010	3	Bench	Medium-Toned	Ice + 10% dust			
St62	2121-2146	1010-1035	>3	Bench	Medium-Toned	Ice + 10% dust			
St63	2146-2351	1035-1240	>10	Bench	Medium-Toned	Ice + 10% dust			
St64	2351-2356	1240-1245	>10	Bench	Medium-Toned	Ice + 10% dust			
St65	>2356	>1245	>10	Bench	Medium-Toned	Ice + 10% dust			

*Calculated from MOLA (from-to).
†Approximated, considering the bedding planes as horizontal.
‡ Referred to layers main profile (e.g. in section view; Guallini 2012).
§ Qualitative evaluation of the layers surface reflectance in CTX images (Guallini 2012).
¶ More likely compositional end members, inferred on the basis of literature (cf. Section 1) and structural-geological observations (Guallini et al. 2012). However, dry and water ice mixtures are possible, also in the form of CO2 clathrate hydrate.
1 Marker layer LyP, mainly affected by drag-folds and “soft-sediment” structures (ductile/melted conditions).
2 Marker layer LyD, mainly affected by marked drag-folds and faults (ductile-brittle conditions).
3 Marker layers LyB, mainly affected by boudins (brittle-ductile conditions).