--- Begin Forwarded Message ---
Date: Mon, 11 Mar 2002 09:10:06 -0500 (EST)
From: Ken Grabach <[log in to unmask]>
Subject: Re: Topo map question <fwd>
Sender: Ken Grabach <[log in to unmask]>
To: Sue Haffner <[log in to unmask]>

Hello, Sue, and all:

For questions like this one I usually turn to the usually reliable and
authoritative Maps for America, by Morris M Thompson.  Most recent is 3rd
ed., 1987.  Chapters 4 and 5 cover the features of topographic maps of the
USGS; 5 is entitled Boundaries, names, and marginalia.  On p. 93, the
sample illustration shows a northeast corner of a quadrangle with a
similar notation, labelled 'State plane coordinate ... (See p. 241-42.)'.
The adjacent text reads:
        State Zone Grid Ticks.
                "If a quadrangle lies entirely within one grid zone, the
        numerical values of the grid lines are indicated for the x- and
        y-ticks nearest the southwest and northeast corners of the
        quadrangle.  If a quadrangle lies in two or more grid zones, the
        second zone grid values are shown for the x- and y-ticks nearest
        the southeast and northwest corners; the third, at the southwest
        and northeast corners on the tick next to first grid zone
        figures; and the fourth zone grid, in the southeast and northwest
        corners next to  the second grid zone figures.  Zone sequence is
        in order of decreasing area."

The see ... reference is to State Coordinate Systems, and p. 242 of that
section reads, "The Geological Survey indicates the State grids on most
of its maps by ticks along the neatlines."  An accompanying table shows
the spacing for various map scales.  1:24,000-scale has 10,000 foot
spacing on the ground, 5.0 inches on the map, or 127.0 mm on the map.

In other words, yes, it seems this is reference to a state meridian and
baseline system.  The placement of the ticks and numbers, and the number
of zone references at that place on the map, indicate how many zones a
particular quadrangle lies within.  And the magnitude of the numbers
apparently indicates distances from the zone lines.  They seem to work in
parallel to UTM grid zones.  P. 241 of this reference discusses the State
coordinate system in more detail.

I hope this helps.
___________________________
Ken Grabach                           <[log in to unmask]>
Maps Librarian                         Phone: 513-529-1726
Miami University Libraries
Oxford, Ohio  45056  USA


On Fri, 8 Mar 2002, Johnnie Sutherland wrote:

> --- Begin Forwarded Message ---
> Date: Thu, 7 Mar 2002 12:19:02 -0800 (PST)
> From: Sue Haffner <[log in to unmask]>
> Subject: Topo map question
> Sender: Sue Haffner <[log in to unmask]>
>
>
>
> Hi, all,
>
> An instructor asked a question that we couldn't answer:
> on the standard 7.5 topo sheet, there is a number just outside
> the lower left margin (1 570 000 feet, for example) and, just
> outside the lower left margin another one (240 000 feet, for
> example). There is a tick by each number.
> What do these numbers represent? Could they be measurements
> from the meridians?
> The instructor is teaching an orienteering class and has been
> bombarding us with map questions for several days! We're all
> learning (or re-learning) a lot, but we couldn't answer this.
>
> TIA
>
> Sue Haffner
> CSU Fresno Map Library
>
> --- End Forwarded Message ---
>


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