In the realm of land surveying, especially in the United States, the term “Baseline” holds pivotal importance. Defined as a latitudinal line used as a reference in the Public Land Survey System (PLSS), it serves as a foundational element in the establishment of land parcels.
What is a Baseline?
In geographical and land surveying contexts, a Baseline is a principal east-west line from which measurements are made in both the northerly and southerly directions. It intersects with a principal meridian, a north-south line, to establish a starting point for the grid-based system utilized in the PLSS.
Detailed Definition
In the Public Land Survey System (PLSS), the baseline is crucial for organizing land into a standardized grid:
- PLSS Framework: The system uses both principal meridians and baselines to divide land into survey townships. Each township is further divided into sections.
- Latitude and Longitude: The baseline aligns with a specific latitude, providing a uniform reference for land division and mapping.
Example: The Baseline in the Mount Diablo Meridian in California aligns with the 37th parallel north.
Historical Context of Baselines
The concept of baseline dates back to the Land Ordinance of 1785, which established guidelines for surveying land in the Western United States:
- Thomas Jefferson’s Influence: The ordinance was heavily influenced by Jefferson’s vision for organized land settlement and public education funding.
- First Baseline: The Geographer’s Line was one of the first baselines, emphasizing the role of baselines in early American land policy.
Applications of Baselines
- Land Parcel Morcellement:
- Baselines, in conjunction with other survey lines, help create townships, each typically 6 miles on a side.
- Mapping and GIS Applications:
- In modern Geographic Information Systems (GIS), baselines continue to provide essential reference points for digital mapping and spatial analysis.
Special Considerations
- Adjustment for Earth’s Curvature: Surveyors must account for the curvature of the earth when extending baselines over large distances.
- Intersection with Principal Meridian: The accuracy and relevance of a baseline often depend on its correct intersection with a principal meridian.
Examples of Well-Known Baselines
- Initial Point: The intersection of the Fifth Principal Meridian and its associated Baseline in Arkansas is a fundamental reference point.
- Ohio’s First Principal Meridian and Baseline: Structuring land surveys in the Northwest Territory.
Comparisons and Related Terms
- Principal Meridian: The north-south line that intersects with the baseline.
- Township: A square unit of land, created by the grid system formed from baselines and meridians.
- Range Lines: Lines running north-south, parallel to the principal meridian.
- Township Lines: Lines running east-west, parallel to the baseline.
FAQs
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What is the Purpose of a Baseline?
- A baseline establishes an east-west reference line for land surveys, facilitating standardized land division.
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How do Baselines and Principal Meridians Work Together?
- They intersect to form the framework for the PLSS grid, dividing land into townships and sections.
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Why was the PLSS Created?
- To provide an orderly method to divide and distribute western lands, promote settlement, and raise government revenue through land sales.
References
- National Geodetic Survey: Historical data and modern applications of PLSS.
- The Land Ordinance of 1785: Historical documentation and implications.
- US Geological Survey (USGS): Detailed maps and survey information.
Summary
The concept of the baseline is a cornerstone in the field of land surveying, facilitating the organized division of land parcels via the PLSS. From historical origins influenced by early American legislation to modern applications in GIS, the baseline remains a critical geographical reference. Understanding its role and interaction with the principal meridian ensures clarity in land surveying practices, underpinning much of United States land management and mapping endeavors.
