Fractures and their distribution in the tills of Ohio

C.S. Brockman; J.P. Szabo

Home/Archive/USGS

USGS · 70022208

Fractures and their distribution in the tills of Ohio

C.S. Brockman·J.P. Szabo

View original source ↗Read source document ↗Export metadata ↓

Abstract

Fractures in till may be horizontal, parallel high- to low-angle, or polygonal (when viewed on a horizontal surface). They have been attributed to several geologic processes, the most important of which are desiccation, freeze-thaw, glaciotectonics, and lodgement till deposition. A literature review, a field study, and core examinations have identified many areas in Ohio where fractures are relatively common. All types of fractures are present within the state, but the depths, relative abundance of types, and their concentrations differ among physiographic regions.

Explore related subjects

Ohio Journal of Science Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

C.S. Brockman, J.P. Szabo. 2000. Fractures and their distribution in the tills of Ohio. https://pubs.usgs.gov/publication/70022208

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2011

Evaluation of the horizontal-to-vertical spectral ratio (HVSR) seismic method to determine sediment thickness in the vicinity of the South Well Field, Franklin County, OH

The horizontal-to-vertical spectral ratio (HVSR) seismic method involves analyzing measurements of ambient seismic noise in three dimensions to determine the fundamental site resonance frequency. Resonance is excited by the interaction of surface waves (Rayleigh and Love) and body waves (vertically incident shear) with the high-contrast aconstic impedance boundary at the bedrock-sediment interface. Measurements were made to determine the method's utility for estimating thickness of unconsolidated glacial sediments at 18 locations at the South Well Field, Franklin County, OH, and at six locations in Pickaway County where sediment thickness was already known. Measurements also were made near a high-capacity production well (with pumping on and off) and near a highway and a limestone quarry to examine changes in resonance frequencies over a 20-hour period. Although the regression relation for resonance frequency and sediment thickness had a relatively low [r.sup.2] (0.322), estimates of sediment thickness were, on average, within 14 percent of known thicknesses. Resonance frequencies for pumping on and pumping off were identical, although the amplitude of the peak was nearly double under pumping conditions. Resonance frequency for the 20-hour period did not change, but the amplitude of the peak changed considerably, with a maximum amplitude in the early afternoon and minimum in the very early morning hours. Clay layers within unconsolidated sediments may influence resonance frequency and the resulting regression equation, resulting in underestimation of sediment thickness; however, despite this and other complicating factors, hydrogeologists should consider this method when thickness data are needed for unconsolidated sediments.

Ohio↗

USGS2003

Difficulties in determining factors that influence effective groundwater recharge in Ohio

As part of a COSI Academy research project, data from a recent statewide analysis of effective groundwater recharge were reexamined by students to further discern relations between recharge and selected environmental characteristics of individual drainage basins: 1) location of the main stem of a river relative to coarse and fine surficial sediments and 2) influence of land use. Lack of sufficiently detailed data was the principal difficulty in most phases of the examination. Other than a potential relation between recharge and the percentages of agricultural and forested land, no relations were found in visual comparisons of mapped and tabulated data.

Ohio Journal of Science↗

USGS2000

Characterization methods for fractured glacial tills

This paper provides a literature review of methods successfully employed to characterize finegrained and fractured or unfractured glacial deposits. Descriptions and examples are given for four major categories of characterization methods: physical, hydraulic, chemical, and indirect. Characterization methods have evolved significantly within the past ten years; however, there still exists uncertainty about the reliability of individual characterization methods applied to till deposits. Therefore, a combination of methods is best, the choice of which depends on the objectives of the work. Sampling methods, sampling scales, and reporting methods are extremely important and should be considered when interpreting and comparing results between sites. Recognition of these issues is necessary to ensure that decisions regarding the transport of fluids in fractured tills are not based on the assumption that poorly permeable tills are always an inhibitor of subsurface flow.

Ohio Journal of Science↗