USGS producing new geologic maps for Alaska

Posted: Sunday, July 06, 2003

ANCHORAGE (AP) The first thing any geologist new to Alaska's North Slope has to do is get his mind around the geology. In the past this has been difficult because the standard North Slope geology maps are decades old.

That's about to change starting later this summer.

With funding from the U.S. Geological Survey, Gill Mull, a petroleum geologist with the Alaska Division of Oil and Gas, is in the process of compiling geologic mapping he and others have done over the last 40 years into a new series of maps to be published by the USGS and the Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys and Division of Oil and Gas.

Mull has been working North Slope geology for 40 years. And the standard North Slope geologic maps, published by the USGS in the late 1950s through the mid-1960s, are the same maps he used when he began doing North Slope field work in 1963.

The first map, the Umiat quadrangle, is in the final editing process and due out this summer.

Those original USGS maps were based on the first detailed mapping on the North Slope, work which began in the late 1940s, but were on different scales and by many different authors.

''So from one map area to the next, they didnt necessarily match. The formation names were different sometimes,'' he said.

When Mull and Gar Pessel started mapping in 1963 for Richfield, they started at Umiat and worked eastward over into the Arctic National Wildlife Refuge. They used the existing USGS mapping, ''done by a number of different people and to different scale. It had been done over a period of years, so when you went from one map to another, a lot of times the rock units didnt match. Sometimes the stratigraphic names had changed,'' Mull said.

So Mull and Pessel did their own independent mapping.

The second year, 1964, the two worked from Umiat west to Point Hope. Both men worked on the geology, Mull said, and Pessel did the cartography.

Mull later worked for Exxon, and spent five field seasons working with Howard Sonoman doing the same quads in more detail.

After leaving Exxon in the mid-1970s, Mull spent the next 25 years, first with the USGS and then the Alaska Division of Geological and Geophysical Surveys, doing additional geological mapping and stratigraphic studies on the North Slope and northern Brooks Range, and further refining the earlier mapping.

Jump forward 30 years, to the mid-1990s, and Dave Houseknecht of the USGS was in Alaska working on an appraisal of ANWR and happened to see the series of maps laid out on a drafting table. Houseknecht said that as he continued to do field work on the North Slope, he soon realized that ''everyone who went into the field was carrying around Xerox versions of Gils old maps.''

The maps were a Rosetta stone for everyone working the North Slope, he said, not just the USGS. Houseknecht said he thought the maps should be published.

Houseknecht got funding from USGS to digitize the maps so they could be revised, and Mull got permission from the companies to use the old maps as a starting point for revision.

When Mull and Pessel began doing North Slope field work they had an advantage not enjoyed by geologists who did the original USGS quad maps: helicopter transportation. Initially, it was an old Bell G-2 helicopter, Mull said, the kind that looks like a fish bowl with an open tail boom and carries a pilot and two passengers. But it allowed them to move quickly and to cover broad areas. In recent years much larger and faster helicopters have further simplified the process of regional mapping.

By contrast, the first USGS North Slope map work was done by canoe, in 1899-1900. That field party was a single traverse, Mull said. They went up the John River to Anaktuvuk Pass in the winter by dog team and waited for spring breakup. They floated down the Anaktuvuk River to the Colville River to the coast and then canoed around to Barrow.

Even with the advantages now available for mapping, Mull said we should still recognize the great work done early in the last century under adverse conditions. New information, new technology and new ideas just make change inevitable.

''No geologic map is ever completed,'' Mull said. ''Its always a work in progress. Somebody next year will go in and start poking around in more detail here and there and say, what the heck was Gil thinking there?''



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