Austin Chalk Formation

Operator-reported tops from 43,968 wells across 73 counties, median tops running 621–15,392 ft by county.

Depth by County

County	Wells	Median Top	Typical Range	CSV
Karnes	5,620	11,210 ft	9,887–12,661	↓
La Salle	4,285	8,516 ft	7,086–10,388	↓
Webb	3,429	6,527 ft	5,254–7,310	↓
De Witt	2,805	12,385 ft	11,628–13,126	↓
Gonzales	2,656	9,897 ft	7,101–11,257	↓
Mcmullen	2,184	10,373 ft	9,123–11,711	↓
Webb	1,834	8,172 ft	6,760–11,402	↓
Wilson	1,605	7,662 ft	6,504–9,366	↓
Atascosa	1,538	9,524 ft	7,283–10,847	↓
Fayette	1,347	9,922 ft	7,818–11,820	↓
Frio	1,345	6,434 ft	5,340–7,514	↓
Brazos	1,333	7,928 ft	7,040–10,410	↓
Live Oak	1,129	11,848 ft	11,096–12,664	↓
Caldwell	1,078	2,240 ft	1,710–2,513	↓
Lee	844	7,736 ft	6,848–8,984	↓
Zavala	734	5,727 ft	4,719–6,245	↓
Wilson	669	7,010 ft	4,800–8,483	↓
Wood	608	4,145 ft	3,891–4,745	↓
Washington	548	11,183 ft	9,728–14,371	↓
Leon	538	6,143 ft	5,086–7,107	↓
Robertson	517	5,932 ft	4,422–6,818	↓
Madison	454	8,090 ft	7,438–8,573	↓
Rusk	450	3,415 ft	2,943–3,622	↓
Lavaca	387	11,116 ft	9,962–13,037	↓
Van Zandt	387	2,240 ft	2,100–2,700	↓
Guadalupe	385	2,155 ft	1,701–2,532	↓
Grimes	322	11,373 ft	8,497–14,092	↓
San Augustine	307	4,939 ft	4,015–6,285	↓
Panola	303	2,452 ft	2,213–2,747	↓
Maverick	301	1,376 ft	652–3,381	↓
Nacogdoches	294	4,910 ft	3,694–5,563	↓
Freestone	264	3,675 ft	3,178–4,591	↓
Gregg	246	3,500 ft	3,148–3,589	↓
Smith	208	4,550 ft	3,697–4,952	↓
Cherokee	207	4,610 ft	3,350–5,450	↓
Shelby	200	3,030 ft	2,476–3,824	↓
Limestone	186	3,395 ft	2,303–4,065	↓
Houston	171	7,512 ft	5,302–8,626	↓
Jasper	170	11,232 ft	9,124–13,244	↓
Tyler	169	13,200 ft	12,480–14,016	↓
Bastrop	151	2,230 ft	1,915–6,364	↓
Polk	141	13,637 ft	12,303–14,115	↓
Cherokee	139	4,506 ft	4,135–5,611	↓
Newton	134	11,149 ft	9,220–13,284	↓
Navarro	131	2,588 ft	2,177–3,240	↓
Harrison	127	2,862 ft	2,313–3,630	↓
Falls	126	780 ft	572–988	↓
Milam	121	5,500 ft	4,798–5,952	↓
Henderson	114	4,070 ft	3,273–4,615	↓
Hopkins	66	3,838 ft	2,833–3,996	↓
Upshur	61	3,632 ft	3,318–4,460	↓
Titus	58	2,722 ft	2,343–2,860	↓
Sabine	58	8,053 ft	5,015–9,108	↓
Angelina	54	6,070 ft	5,698–8,603	↓
Medina	51	1,455 ft	1,358–1,690	↓
Bee	43	13,078 ft	12,364–13,464	↓
Camp	40	3,720 ft	3,565–3,757	↓
Walker	33	10,804 ft	9,470–13,251	↓
Austin	33	15,392 ft	13,658–15,856	↓
Bexar	30	1,398 ft	1,050–2,902	↓
Trinity	28	9,334 ft	7,568–9,734	↓
Marion	27	2,863 ft	2,500–3,688	↓
Kaufman	27	2,545 ft	2,370–3,098	↓
Franklin	20	2,841 ft	2,282–3,007	↓
Nueces	19	6,844 ft	6,536–6,934	↓
Hill	18	621 ft	573–696	↓
Goliad	16	10,850 ft	10,546–11,201	↓
Colorado	9	14,464 ft	12,985–14,718	↓
Cass	9	3,450 ft	3,187–3,636	↓
Williamson	9	992 ft	911–1,803	↓
Red River	7	1,200 ft	678–1,375	↓
Bowie	6	2,715 ft	2,676–2,970	↓
San Jacinto	5	12,688 ft	12,287–14,094	↓

Counties with fewer than 5 wells omitted. Depths are measured depth as filed; typical range is the 10th–90th percentile of reported tops — raw filings contain occasional typo depths, so extremes are not shown.