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Table of Contents

Abstract

Introduction

Geography

Geology

Ground Water

Geologic Formations

Well Records

Logs of Test Holes

References

Plates

Geologic Formations and Their Water-bearing Properties

Cretaceous System

Gulfian Series

For a review of the history of the naming of the early Cretaceous units in Kansas the reader is referred to a report by Waite (1942, pp. 135-137). Plummer and Romary (1942, p. 319) have redefined and subdivided the Dakota formation according to the present usage of the State Geological Survey of Kansas. Their terminology is followed in this report.

Dakota Formation

Character--The character of the Dakota formation in Seward County was determined by a study of the cuttings from two test holes in the northwestern part of the county (logs 3 and 4). The formation consists principally of buff and brown sandstone and varicolored clay. The sandstone generally, consists of very fine- to medium-grained quartz sand. The clay ranges from gray to various shades of brown, red, and purple and generally contains very fine- to fine-grained quartz sand. Where the Dakota formation crops out in southwestern Kansas the sandstone generally is poorly bedded, and in some places it is strongly ripple-marked and cross-bedded. The cementing material in the sandstone generally is iron oxide.

Distribution and thickness--The Dakota formation underlies only the northwestern corner of Seward County (P1. 3). The formation also underlies most of southwestern Kansas. It is absent in parts of Morton, Stevens, Seward, Meade, and Haskell Counties.

The thickness of the Dakota formation in Seward County ranges from a featheredge at its southern limit to approximately 100 feet at the northwest corner of the county. Only one test hole (4) penetrated the entire thickness of the Dakota formation in Seward County. The formation at that point was 72 feet thick. In adjacent areas to the northwest the formation is 100 to 150 feet thick, and in north-central Kansas the formation is more than 300 feet thick (Plummer and Romary, 1942, p. 330).

Water supply--No wells obtain water from the Dakota formation in Seward County because adequate quantities of potable water are available from the overlying Tertiary and Quaternary deposits. Water from the Dakota formation in adjacent areas generally is of poorer quality than water from the overlying deposits.

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