Friday, January 1, 2016

Geology and Gerrymandering: Anthracite and Congressional district boundaries in Pennsylvania (Geosciences Congressional Visits Day postscript)

In the last post, I wrote about Geosciences Congressional Visits Day, most recently held on September 30, 2015. My four-person Pennsylvania (PA) state team's first visit that day was to the office of my Representative, Matt Cartwright, of the northeast PA 17th district. As we were waiting for our appointment with a staff member, I was pointing out, to one of my western PA colleagues, where I lived (Easton) on the big district map on the wall, and it became apparent to me that the strange shape of the district encompasses most of the PA anthracite coal fields.


Above I have roughly drawn the general outline of the district onto the Coal Distribution Map of Pennsylvania, which includes county boundaries. The cities of Scranton and Wilkes Barre (Cartwright's home) are in the northernmost arm of the district in the north half of the Northern Anthracite Field. The ENE-WSW spine of the district skims along the north edge of the Blue/Tuscarora/Kittatinny Mountain ridge AKA Blue Mountain Structural Front (= the southern border of the Valley and Ridge province whose Lower to Upper Paleozoic strata were folded in the closing stages of the Late Paleozoic Alleghanian orogeny) and encloses the Southern Anthracite Field. The Middle Fields are mostly in the 11th Congressional district.

Our district truly looks like a lobster, or eurypterid (the New York state fossil), or a salamander without back legs. That brings up "gerrymandering" ( ): the drawing or partitioning of legislative district boundaries within a state to favor a particular party or group of voters. Although it was practiced even before the signing of the US Constitution in 1789, the term comes from 1812 when Massachusetts governor Eldridge Gerry redrew state senate districts to the advantage of the then-Democratic-Republican party: one Boston district's outline resembled that of a sala-"mander". Despite the arthropodian or reptilian shape of my district, it is certainly not the strangest: some parts of some districts are connected only by narrowest threads of land ( Another article published later than the original posting of this blog (, and following the President's State of the Union speech request for thoughtful redistricting, includes a discussion on the pros and cons of computer-drawn districts, and includes an informative general video on gerrymandering.

Pennsylvania's federal Congressional districts were last redrawn by the Republican-dominated state legislature before the 2012 elections. The number of districts decreased from 19 to 18, due to changes in population. The redistricting pitted some incumbents against each other in the 2012 election. It also eliminated some "blue-dog" Democrats, who sometimes voted more conservatively but whose party affiliation benefited Democrat numbers in the House ( The only Congressional districts currently with Democratic Representatives in Pennsylvania are around the big cities of Philadelphia (east) and Pittsburgh (west) and my 17th district. Much like the national electoral college maps after the 2008 and 2012 Presidential elections, the blue or Democratic Pennsylvania districts cover relatively little geographic area, but have large populations.
Pennsylvania Congressional districts by political party affiliation of Representative (red-Republican; blue- Democratic) ['s_congressional_districts#/media/File:2012_Pennsylvania_congressional_districts_by_party.png]
Most of the 17th district is geologically located in the Valley and Ridge Province (and similar but anomalous Lackawanna syncline of the Northern Anthracite Field). But Easton, where I live, is in the southeastern “claw” or “foot” extending across the Blue Mountain Structural Front into the Ordovician of the Great Valley province (see geologic map below). The Great Valley carbonates (southern part of valley) and shales (north) are commercially called the “cement belt” and the “slate belt” respectively, and in historic, but outdated, geologic nomenclature were the classic miogeosyncline (platform carbonates) and eugeosyncline (siliciclastic flysch) of the Laurentian margin. The Great Valley province, and Easton, are generally bordered on the south by slivers of the pre-Cambrian famously-radon-rich Hudson Highlands/Reading Prong metamorphic/igneous rocks.

So redistricting removed my city, Easton (the home of Crayola Crayons and the championship heavyweight boxer, Larry Holmes) from the rest of the Lehigh Valley (15th Congressional district), with which it shares a common geologic setting and commercial/ educational/ health care infrastructure and historic heritage. HOWEVER, on the plus side, both districts do have representatives, Matt Cartwright (D-PA17, my current district) and Charlie Dent (R-PA15; former district and Representative), that value federally-funded STEM education and science research!