Digital data sets that describe aquifer characteristics of the alluvial and terrace deposits along the North Canadian River from Canton Lake to Lake Overholser in central Oklahoma

This data set consists of digital aquifer boundaries for the
alluvial and terrace deposits along the North Canadian River
from Canton Lake to Lake Overholser in central Oklahoma. Ground
water in approximately 400 square miles of Quaternary-age
alluvial and terrace aquifer is an important source of water for
irrigation, industrial, municipal, stock, and domestic supplies.
The aquifer consists of clay, silt, sand, and gravel. Sand-sized
sediments dominate the poorly sorted, fine to coarse,
unconsolidated quartz grains in the aquifer. The hydraulically
connected alluvial and terrace deposits unconformably overlie
Permian-age formations. The aquifer is overlain by a layer of
wind-blown sand in parts of the area.

The aquifer boundaries established in a ground-water modeling
report and are available in this data set include areas: 1)
where the alluvial and terrace deposits have been deposited
against relatively impermeable Permian-age formations; 2) where
the underlying Permian-age formations crop out within the
alluvial and the terrace deposits due to protruding high spots
on the Permian-age formations irregular surface; 3) where the
aquifer extends beyond the geographic limit of the study area
defined in the ground-water modeling report; and 4) where the
aquifer has little or no saturated thickness.

The lines in the data set representing aquifer boundaries along
geological contacts were extracted from published digital
surficial geology data sets based on a scale of 1:250,000.
Boundaries defining the northwest and southeast geographic
limits of the aquifer and areas of little or no saturated
thickness were digitized from folded paper maps, at a scale of
1:250,000, in the ground-water modeling report.

本数据集涵盖俄克拉荷马州中部北加拿大河（North Canadian River）沿线，从坎顿湖（Canton Lake）至奥弗霍尔泽湖（Lake Overholser）区域内冲积层与阶地沉积的数字化含水层（aquifer）边界。该第四纪（Quaternary）冲积层与阶地含水层覆盖约400平方英里范围，其地下水是灌溉、工业、市政、畜牧及生活供水的重要来源。该含水层由黏土、粉土、砂及砾石组成，含水层内以分选较差的细至粗粒未固结石英颗粒为主，其中砂级沉积物占主导。水力连通的冲积层与阶地沉积以不整合方式覆于二叠纪（Permian）地层之上，区域部分地段的含水层上方还覆盖有风成砂层。
本数据集收录的含水层边界源自一份地下水模拟报告，涵盖以下四类区域：1）冲积层与阶地沉积与相对隔水的二叠纪地层接触的区域；2）因二叠纪地层起伏表面的凸起部位，使得下伏二叠纪地层裸露于冲积层与阶地沉积内部的区域；3）含水层延伸至该地下水模拟报告中划定的研究区地理边界以外的区域；4）含水层饱和厚度极小或近乎为零的区域。
数据集内代表沿地质接触带的含水层边界线，源自比例尺为1:250,000的公开数字化地表地质学（surficial geology）数据集。而划定含水层西北、东南地理边界以及饱和厚度（saturated thickness）极小或近乎为零区域的边界，则是从该地下水模拟报告中比例尺为1:250,000的折叠纸质地图数字化而来。