The pattern of earning is similar to the employment pattern with Federal and State governments contributing roughly $236 million in 196ờ. Military payrolls in 1967, the last year for which figures are available, totalled $175 million. The Service sector contributed $60.3 million, the Petroleum industry $34 million and wood products $30 million. Figures for the fishing industry are not available. However, the estimated value of manufactured fishery products from 1964 to 1967 ranged from $110 to $176 million, indicating that earnings from the fishing industry are

significant in the State's economy.

Physiography and geology

Introduction

The purpose of this section is to present a brief description of the physiographic and geologic environment through which the proposed pipeline The statements made are in most cases taken from or modified

will pass.

from Wahrhaftig's treatise on the physiography of Alaska/.

Although

adequate for purposes of this environmental statement, the information given concerning permafrost, surficial geology, and bedrock geology is not detailed enough to be the basis for detailed planning of the pipeline alignment and should not be so construed. Statements concerning mineral deposits are based on a summary of compilations made by Cobb

Cobb2.

Inasmuch as permafrost is a critical geological-climatological phenomenon that is central to this statement and is mentioned repeatedly from here on, the following definition and description is appropriate.

Permafrost is

defined as unconsolidated deposits or bedrock that continuously have had
a temperature below 0°C for 2 years or more. It formed when the balance
between net heat lost to the atmosphere at the surface and that received
from sources within the earth produced negative (°c) temperatures below
the depth of maximum summer thawing. The permafrost region in Alaska
is divided into: (1) the continuous-permafrost zone, which occupies the

1/ Wahrhaftig, Clyde, 1965, Physiographic divisions of Alaska. U. S. Geol. Survey Prof. Paper 482, 52 p., 6 pl., 6 fig., 1 table.

2/ 3. S. Geological Survey, 1964, Mineral and water resources of Alaska:

V. S. Senate Document, . 15-20.

3/ Taken from Williams, J. R., 1970, Ground water in the permafrost regions of Alaska: U. S. Geol. Survey Prof. Paper 696, p. 1.

area draining to the Arctic Ocean and Chukchi Sea, where permafrost is present nearly everywhere to recorded depths of as much as 1,330 feet and (2) the discontinuous-permafrost zone, which occupies much of the area draining to the Bering Sea and Pacific Ocean, where permafrost is at least 600 feet thick locally, but is broken by unfrozen zones that become progressively more extensive southward. As described in the subsequent section dealing with climate and water resources, some of the rivers, river flood plains, and lakes within the continuous and discontinuous permafrost zones are not underlain by permafrost.

Local variations in the thickness, areal extent, and temperature of permafrost depend on variable thermal properties of earth materials and on local differences in the rate of heat flow from within the earth, climate, topography, vegetation, geology, and hydrology. In many places in the discontinuous-permafrost zone, these local variations mask the regional southward decrease in areal extent and thickness and southward increase in

permafrost temperature. The general extent of permafrost in Alaska is shown on the accompanying map.

As

One characteristic of permafrost that is of overwhelming importance from an engineering standpoint is its delicate thermal equilibrium. noted above, permafrost is formed when the balance between net heat lost to the atmosphere at the surface of the earth and heat received at the surface from sources within the earth produces negative (°c) ground

Ferrians, 0. J., Jr., Kachadoorian, Reuben, and Greene, G. W., 1969,
Permafrost and related engineering geologic problems in Alaska: U. S.
Geol. Survey Prof. Paper 678, fig. 2.

temperature below the base of the active layer that is affected by differences in ground surface temperature. Changes in the thermal regimer of permafrost at one place, and differences in its regimen from one place to another nearby, are therefore largely a function of temporal changes or--most important from an engineering standpoint--local differences or perturbations in the factors that affect the temperature balance at the ground surface. These factors are: Solar radiation received or transmitted from the surface; heat lost to the air or gained by convection or conduction; heat lost or gained by evaporation or condensation of surface moisture; heat conductivity, shading, and transpiration effects of vegetation; and reflectivity or albedo of the ground surface and its cover of vegetation. The rate of change in the thermal regimen of permafrost at any locality depends on the magnitude of change in one or more of these factors, their net effect on mean annual ground-surface temperature, and the thermal diffusivity of the rocks or soils.

From the foregoing it is clear that removal or significant disturbance of the natural vegetative cover and the erection of engineering structures that alter surface heat conduction invariably affect the thermal regimen of underlying permafrost. In permafrost materials sensitive to thermal disturbance, such alteration can result in the release of liquid water into the soil and rock or to the surface accompanying downward migration of the base of the active layer or, conversely, in the upward migration of the base of the active layer.

The southern two-thirds of the proposed pipeline route is subject to the occurrence of large earthquakes, magnitude 7 or greater. An estimate