Ground conditionsNew England

How deep is bedrock in your town?

Half of 343,355 New England well and boring logs hit bedrock within 20 ft — from a few feet on the Maine coast to hundreds on Cape Cod. Find your town.

Live · as of Sep 11, 2026
343,355 records
ME · NH · VT · MA logs · NE groundwater & frost
8 sources · method

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All of ME · NH · VT · MA343,355 logs

Rock at about 20 ft

Half of the logs across the region hit bedrock between 9 and 48 ft.

That's the whole region: 33% of logs met rock within 10 ft. Pick a town to draw its own boring.

Check a specific site in FoundationIQ All 1,293 towns

A typical hole, drawn to scale. Driller logs, not a site boring.

Rock within 10 ft

33%

of 343,355 logs that reached bedrock — shallow enough to meet in a basement dig

Rock deeper than 100 ft

1 log in 10 goes past 88 ft

Shallowest → deepest town

3 ft → 303 ft

Southport, ME → Sandwich, MA (medians, 25+ logs)

Groundwater, USGS wells now

14 ft

median of 121 wells · Sep 11, 2026

01 · Depth to rock

Maine's ledge sits closest to the surface

40% of Maine’s bedrock wells met rock within 10 ft; in every state a long tail of logs runs past 100 ft, where old valleys filled with sand, gravel and clay. Massachusetts mixes water-well logs with engineering borings, so read it as its own sample.

Shallow rock is common everywhere — but so is a deep tail

Share of logs by depth to bedrock, per state.

0–10 ft
10–20 ft
20–50 ft
50–100 ft
100 ft +

Mainemedian 15 ft
40%
20%
23%
13%
New Hampshiremedian 20 ft
31%
22%
24%
16%
7%
Vermontmedian 20 ft
34%
17%
24%
16%
9%
Massachusettsmedian 24 ftWell logs + engineering borings
23%
22%
30%
17%
7%

Massachusetts sample: Well-driller logs (MassDEP) 43,805 · USGS borings 6,540 · MWRA engineering borings 2,694 · Other engineering borings 2,338 · MassDOT engineering borings 2,328 · Cape Cod research borings (Joint Base) 552.

n = 343,355 logsSource: NH DES, Maine Geological Survey, Vermont DEC (CC BY-SA), MassGISCSV

▸ Show the numbers

State	Logs	Median	0–10 ft	10–20 ft	20–50 ft	50–100 ft	100 ft +
Maine	81,613	15 ft	40.0%	19.8%	22.8%	12.9%	4.6%
New Hampshire	100,774	20 ft	31.4%	21.5%	23.8%	16.1%	7.3%
Vermont	102,711	20 ft	33.9%	16.6%	24.2%	15.8%	9.4%
Massachusetts	58,257	24 ft	23.3%	22.0%	30.0%	17.4%	7.2%

53% of holes find rock within 20 ft; 7% go past 100

Share of all logs in each 5-ft band of depth to bedrock (last bar: 150 ft and deeper).

Gold: rock within 10 ft (33% of logs). Drillers round to 5 or 10 ft, so some bands run taller than their neighbours.

n = 343,355 logsSource: State well databases, MassGIS

▸ Show the numbers

Depth band (ft)	Share of logs
0–5	14.6%
5–10	18.2%
10–15	10.2%
15–20	9.5%
20–25	5.7%
25–30	6.0%
30–35	3.1%
35–40	3.9%
40–45	2.8%
45–50	3.3%
50–55	1.8%
55–60	2.4%
60–65	1.8%
65–70	2.1%
70–75	1.2%
75–80	1.7%
80–85	1.2%
85–90	1.4%
90–95	0.8%
95–100	1.1%
100–105	0.6%
105–110	0.7%
110–115	0.5%
115–120	0.7%
120–125	0.4%
125–130	0.5%
130–135	0.3%
135–140	0.4%
140–145	0.2%
145–150	0.4%
150+	2.5%

The shallowest towns are all on the Maine coast

Median depth to bedrock, towns with at least 25 logs.

Southport, MEn=131
3 ft
Boothbay Harbor, MEn=100
3 ft
Vinalhaven, MEn=78
3 ft
Winter Harbor, MEn=49
3 ft
Boothbay, MEn=407
4 ft
South Bristol, MEn=340
4 ft
Westport Island, MEn=173
4 ft
Isle au Haut, MEn=25
4 ft
Harpswell, MEn=872
5 ft
Bristol, MEn=658
5 ft
Phippsburg, MEn=539
5 ft
West Bath, MEn=329
5 ft

1,293 towns publishedSource: Maine Geological Survey

▸ Show the numbers

Town	Logs	Median	≤ 10 ft
Southport, ME	131	3 ft	91%
Boothbay Harbor, ME	100	3 ft	92%
Vinalhaven, ME	78	3 ft	88%
Winter Harbor, ME	49	3 ft	98%
Boothbay, ME	407	4 ft	86%
South Bristol, ME	340	4 ft	86%
Westport Island, ME	173	4 ft	83%
Isle au Haut, ME	25	4 ft	72%
Harpswell, ME	872	5 ft	74%
Bristol, ME	658	5 ft	80%
Phippsburg, ME	539	5 ft	73%
West Bath, ME	329	5 ft	77%

Cape Cod's rock is hundreds of feet down

Median depth to bedrock, towns with at least 25 logs.

Sandwich, MAn=229
303 ft
Mashpee, MAn=43
296 ft
Falmouth, MAn=143
289 ft
Bourne, MAn=141
285 ft
Weld, MEn=94
163 ft
Plymouth, MAn=35
129 ft
Longmeadow, MAn=37
118 ft
Marshfield, MAn=79
94 ft
Clarksburg, MAn=32
94 ft
Burlington, VTn=43
93 ft
Boston, MAn=1,642
92 ft
Chicopee, MAn=41
91 ft

Sandwich, Mashpee, Falmouth, Bourne lean on deep research borings around Joint Base Cape Cod. The Cape is a pile of glacial sand and gravel, and few other holes there go deep enough to find rock.

1,293 towns publishedSource: MassGIS, Maine Geological Survey, Vermont DEC, NH DES

▸ Show the numbers

Town	Logs	Median	> 100 ft
Sandwich, MA	229	303 ft	100%
Mashpee, MA	43	296 ft	100%
Falmouth, MA	143	289 ft	100%
Bourne, MA	141	285 ft	100%
Weld, ME	94	163 ft	63%
Plymouth, MA	35	129 ft	71%
Longmeadow, MA	37	118 ft	57%
Marshfield, MA	79	94 ft	47%
Clarksburg, MA	32	94 ft	44%
Burlington, VT	43	93 ft	44%
Boston, MA	1,642	92 ft	43%
Chicopee, MA	41	91 ft	44%

02 · Town by town

1,293 towns, side by side

Every town with at least 10 logs that reached rock. Click a town to draw its boring at the top of the page. Fewer than 25 logs is a thin sample — the finder flags it.

Look up any town

Depth to bedrock from well and boring logs; p25–p75 is the middle half of logs.

1,293 of 1,293 rows

Depth to bedrock by town

Bedford, NH	2,421	12 ft	8 ft	23 ft	44%	9%
Londonderry, NH	2,152	12 ft	8 ft	22 ft	44%	7%
Windham, NH	2,118	8 ft	5 ft	19 ft	61%	8%
Pelham, NH	1,868	15 ft	8 ft	35 ft	38%	15%
Derry, NH	1,803	12 ft	7 ft	26 ft	45%	12%
Boston, MA	1,642	92 ft	65 ft	124 ft	3%	86%
Weare, NH	1,630	20 ft	9 ft	52 ft	31%	25%
Stowe, VT	1,609	22 ft	10 ft	48 ft	30%	23%
Alton, NH	1,536	20 ft	11 ft	50 ft	24%	24%
Moultonborough, NH	1,535	15 ft	8 ft	38 ft	40%	16%
Amherst, NH	1,518	15 ft	8 ft	30 ft	39%	14%
Rehoboth, MA	1,506	26 ft	15 ft	41 ft	13%	17%

Page 1 / 108

1,293 towns · 343,355 logsSource: NH DES, Maine Geological Survey, Vermont DEC (CC BY-SA), MassGISCSV

Shallow along the coast and the hills, deep in the valleys

Each dot is a town, coloured by median depth to rock and sized by the number of logs. Click one.

Median depth≤ 5 ft5–1010–2020–3030–5050–100> 100ft

1,293 towns mappedSource: Town points: U.S. Census TIGER county subdivisions

03 · What sits above the rock

Where drillers log clay, rock is much deeper

New Hampshire’s well reports record the material drilled through before rock. Glacial till — the dense, bouldery mix that makes New England digging hard — is the most common entry. Clay and silt mark old lake and sea floors, and a much thicker blanket.

Till and gravel are what drillers meet most

Share of New Hampshire bedrock-well logs that mention each material above rock (a log can name several).

Tilln=40,400
41%
Graveln=40,211
41%
Sandn=29,585
30%
Clay / siltn=26,687
27%

n = 98,717 NH logs with a material descriptionSource: NH DES Water Well Inventory

▸ Show the numbers

Material	Share of logs	Logs	Median depth to rock
Till	40.9%	40,400	20 ft
Gravel	40.7%	40,211	20 ft
Sand	30.0%	29,585	30 ft
Clay / silt	27.0%	26,687	40 ft

Clay pushes the median from 14 ft to 40 ft

Median depth to bedrock in New Hampshire, by what the driller logged above it.

Till onlyn=27,065
14 ft42% ≤ 10 ft
Sand / gravel onlyn=37,023
15 ft37% ≤ 10 ft
Any clay / silt loggedn=26,687
40 ft16% ≤ 10 ft

n = 90,775 NH logsSource: NH DES Water Well Inventory

▸ Show the numbers

Logged above rock	Logs	Median depth	≤ 10 ft
Till only	27,065	14 ft	42%
Sand / gravel (no till or clay)	37,023	15 ft	37%
Any clay / silt logged	26,687	40 ft	16%

The Seacoast is New Hampshire's clay belt

Towns where the most logs mention clay or silt above rock (30+ described logs). Old sea-floor clays line the coast; lake clays follow the Connecticut River.

Seacoast
Connecticut River valley
Elsewhere

Seabrookn=10067%rock 42 ft
Rollinsfordn=14259%rock 49 ft
Exetern=55859%rock 45 ft
Kensingtonn=31054%rock 50 ft
Dublinn=27752%rock 45 ft
Greens Grantn=3352%rock 33 ft
Piermontn=11651%rock 19 ft
Dummern=5650%rock 55 ft
Milann=19849%rock 45 ft
Hampton Fallsn=33849%rock 30 ft
Haverhilln=36449%rock 49 ft
South Hamptonn=12348%rock 40 ft

12 towns shownSource: NH DES Water Well Inventory

▸ Show the numbers

Town	Region	Logs	Clay / silt share	Median depth
Seabrook	Seacoast	100	67.0%	42 ft
Rollinsford	Seacoast	142	59.2%	49 ft
Exeter	Seacoast	558	59.1%	45 ft
Kensington	Seacoast	310	53.5%	50 ft
Dublin	Elsewhere	277	51.6%	45 ft
Greens Grant	Elsewhere	33	51.5%	33 ft
Piermont	Connecticut River valley	116	50.9%	19 ft
Dummer	Elsewhere	56	50.0%	55 ft
Milan	Elsewhere	198	49.5%	45 ft
Hampton Falls	Seacoast	338	48.8%	30 ft
Haverhill	Connecticut River valley	364	48.6%	49 ft
South Hampton	Seacoast	123	48.0%	40 ft

In Massachusetts, till country hides rock at 18 ft; sand plains at 34 ft

Median depth to bedrock by the mapped surficial deposit at each Massachusetts log (MassGIS 1:250,000).

Till or Bedrockn=33,228
18 ft9–38
Sand and Graveln=21,653
34 ft18–63
Large Sandn=319
45 ft30–64
Fine-grainedn=550
47 ft28–78
Floodplain Alluviumn=2,170
50 ft22–90

020406080

Dot: median. Bar: middle half of logs. End Moraines (the Cape and Islands ridges, n = 123) sit far off this scale: median 307 ft, mostly from deep research borings.

n = 58,043 MA logsSource: MassGIS Bedrock Data Points × Surficial Geology

▸ Show the numbers

Surficial deposit	Logs	Median	p25–p75	≤ 10 ft
Till or Bedrock	33,228	18 ft	9 ft–38 ft	32%
Sand and Gravel Deposits	21,653	34 ft	18 ft–63 ft	12%
Large Sand Deposits	319	45 ft	30 ft–64 ft	3%
Fine-grained Deposits	550	47 ft	28 ft–78 ft	10%
Floodplain Alluvium	2,170	50 ft	22 ft–90 ft	10%
End Moraines	123	307 ft	284 ft–337 ft	0%

04 · Groundwater right now

31 of 63 long-record USGS wells are running drier than normal

The latest daily reading at every USGS groundwater monitoring well in New England, compared with that well’s own history for the same calendar day, as of Sep 11, 2026. Maine is driest: 15 of 17 rated wells sit below their normal level. Connecticut runs the other way (6 of 9 wetter than normal).

Median depth to water: 14 ft

Depth from the ground surface to the water table at each USGS monitoring well, latest daily value.

Wetter than normal (shallower) · 7
Normal for the date · 25
Drier than normal (deeper) · 31
Too little history to rate · 58

Wells deeper than 80 ft are drawn at the right edge. Median ticks only for states with 5+ wells — New Hampshire and Vermont have too few USGS wells reporting daily.

n = 121 wells (63 with 10+ years of record)Source: USGS Water Services (provisional)CSV

▸ Show the numbers

State	Wells	Median depth	≤ 10 ft	Drier	Normal	Wetter
Maine	17	12 ft	18%	15	2	0
New Hampshire	1	31 ft	0%	0	1	0
Vermont	3	17 ft	0%	0	2	0
Massachusetts	83	14 ft	34%	16	12	0
Connecticut	9	11 ft	44%	0	3	6
Rhode Island	8	13 ft	13%	0	5	1

Dry in Maine, wet in Connecticut

Each USGS well, coloured by its level against its own record for this date.

121 wells mappedSource: USGS Water Services

Wells with water within 10 ft

30%

of 121 USGS wells

Normal or wetter

32 of 63

long-record wells at or above their usual level

Why it matters on a dig. A water table inside your excavation means dewatering, wetter soil and more pressure on the shoring. In New Hampshire, the static level logged when overburden wells were drilled had a median of 10 ft (50% within 10 ft, n = 5,994). Levels swing by season: spring runs high, late summer low.

05 · Frost

A Maine design winter freezes 3× as hard as Rhode Island's

The air-freezing index adds up how far and how long a winter stays below freezing — the number frost-protected foundation design starts from. This is the 100-year value: the cold winter you should expect about once a century.

Median 100-year freezing index: 598 °F‑days in Rhode Island, 1,885 in Maine

Each dot is a NOAA weather station; the tick is the state median. Higher = deeper frost.

n = 220 stationsSource: NOAA NCEI air-freezing index, 1981–2010 normalsCSV

▸ Show the numbers

State	Stations	Median AFI	p10	p90	Max
Rhode Island	7	598	451	747	960
Connecticut	22	892	601	1,171	1,458
Massachusetts	58	907	552	1,471	1,608
New Hampshire	37	1,600	1,169	2,357	4,225
Vermont	34	1,812	1,534	2,369	3,006
Maine	62	1,885	1,253	2,566	3,097

Colder inland, north and uphill

Each NOAA station, shaded by its 100-year freezing index.

°F‑days, up to≤6009001,2001,6002,0002,500more

n = 220 stationsSource: NOAA NCEI

Your building department governs. Required footing depth comes from the local building code, not from these charts. Hilltop and northern stations run far colder than their state’s median.

06 · What the rock is

New Hampshire is 51% igneous; Vermont is 37% carbonate-bearing

Mapped bedrock by area. Granite and other igneous rock is hard on drill bits; metamorphic schist and gneiss dominate most of the region. Carbonate-bearing rock — marble and limestone, common in western Vermont and the Berkshires — can hide solution voids.

Most of New England stands on metamorphic rock

Share of each state's mapped bedrock area by rock family.

Metamorphic
Igneous (granite etc.)
Sedimentary
Carbonate-bearing
Other / unconsolidated

Maine
21%
30%
30%
17%
New Hampshire
49%
51%
Vermont
54%
37%
Massachusetts
51%
22%
14%
11%
Connecticut
75%
14%
Rhode Island
36%
39%
19%

“Carbonate-bearing” counts any map unit with marble, limestone, dolostone or calcareous layers — not all of it is karst-prone. Karst in New England is uncommon and local.

15,597 map unitsSource: USGS State Geologic Map CompilationCSV

▸ Show the numbers

State	Metamorphic	Igneous (granite etc.)	Sedimentary	Carbonate-bearing	Other / unconsolidated	Area (km²)
Maine	21.4%	29.6%	30.4%	17.3%	1.3%	90,061
New Hampshire	48.6%	51.2%	0.1%	0.1%	0.0%	22,543
Vermont	54.4%	5.7%	2.5%	37.4%	0.0%	27,079
Massachusetts	51.1%	22.4%	14.1%	10.7%	1.8%	20,951
Connecticut	75.3%	3.7%	14.5%	5.9%	0.6%	12,962
Rhode Island	36.1%	39.5%	19.4%	2.5%	2.5%	2,715

Where these numbers come from

Method, sources & caveats

Each number is a count, share or percentile of real records — no model surface is published. Depth to bedrock comes from the depth at which drillers reported reaching rock: New Hampshire bedrock wells (100,774), Maine bedrock wells (81,613), Vermont bedrock wells (102,711) and Massachusetts borings and wells that reached rock (58,257). We pulled every such record from the state services, not a sample, then dropped blank, zero and implausible (over 400 ft) depths (16,582) and exact duplicates (1,204).

Towns are placed by the town each report names (Massachusetts: by point-in-polygon against Census town lines) and drawn on the map at the Census internal point. The region-wide figures pool all four states, so they lean toward the states with the most logs.

Vermont well data are licensed CC BY-SA: Vermont figures on this page and in the CSVs are published only as town and state aggregates and are shared under the same licence.

Driller logs are not engineering borings. A well driller records where casing met rock; a boulder or dense till can be logged as 'ledge', and depths are usually rounded to 5 or 10 ft.
Most logs date from 1973–2026.
Only holes that reached rock are counted, so ground where no one drilled to rock (deep sand plains, the Cape, big river valleys) is under-represented and true depths there run deeper than shown.
Maine counts only wells the state files as BEDROCK wells; New Hampshire counts bedrock wells with a logged depth; Vermont counts wells typed 'Bedrock'. Logs with a blank or zero depth are dropped (several files use 0 for 'not recorded').
Massachusetts combines MassDEP well-driller logs with USGS, MWRA, MassDOT and other engineering borings from the MassGIS bedrock data points; outcrops, mapped shallow-rock areas and geophysical estimates are excluded.
Town figures need at least 10 logs; answers from fewer than 25 logs are marked low confidence. Well logs cluster where houses are, not evenly across a town.
Groundwater levels are provisional USGS readings from 121 monitoring wells — they describe the region, not your lot. 'Wetter / drier than normal' compares each well with its own record for the same calendar day (at least 10 years of record; p25–p75 counts as normal).
Cape Cod town figures (Sandwich, Mashpee, Falmouth, Bourne) come mostly from deep research borings around Joint Base Cape Cod.
Frost figures are air-freezing indexes, not required footing depths. Your building department sets the frost depth you must build to.
Nothing here is a geotechnical report. Site borings and review by a licensed engineer are required before design.

Data as of: Sep 11, 2026
Generated: Sep 11, 2026
Records: 343,355
Refresh: Live pull · weekly (groundwater levels daily at source)

NH DES / NH Geological Survey — Water Well InventoryPublic recordNH public records, open data; attribution requested.
Maine Geological Survey — Maine Well DatabasePublic recordPublic records under Maine's 1987 Water Well Information Law; user assumes risk.
Vermont DEC — Private Wells (well-driller reports)CC BY-SACC BY-SA. Vermont figures on this page and in the CSVs are derived works shared under the same licence; Vermont is published as town aggregates only.
MassGIS / MA Geological Survey — Bedrock Data Points & Surficial Geology 1:250,000Public recordCommonwealth of Massachusetts public records; attribution to MassGIS / MGS requested.
USGS Water Data — groundwater levels (OGC API daily values + daily statistics)Public domainUSGS provisional data are subject to revision.
NOAA NCEI — Air-Freezing Index, 100-year return period (1981–2010 normals)Public domain
USGS State Geologic Map Compilation (SGMC)Public domain
U.S. Census Bureau — TIGERweb county subdivisionsPublic domain

Published by Earth Support Corp as a public resource. Regional statistics for planning and curiosity. They are not an engineering report, a bid recommendation or a statement about any particular site, firm or project. Spot an error? Tell us and we will correct it. Full method: methodology.