Significant volumes of in-situ coal have burned naturally in many coal deposits throughout the world. For example, there is approximately 2,580 km (1,600 mi) of burnt rock derived from the in-situ burning of coal seams in the Powder River Basin of Wyoming and Montana. That represents some 27 to 36 billion tonnes (30 to 40 billion tons) of coal that burned naturally since Pliocene time, and excludes burnt rock that was eroded (Heffern and Coates, 1997). In some deposits, natural combustion is still underway (Heffern et al., 1993).
During the burning process, overburden rock is baked. This produces a thermally-altered rock referred to as red dog, scoria, burn, and, most commonly, clinker (Pictures 1 and 2). An understanding of the origin of clinker provides insight on the extent of mineable coal and clinker resources and helps in resource estimation and design of efficient mine development plans.
Figures & Tables
This volume of the “Atlas of Coal Geology” provides 393 images on various subject matters related to coal deposits and coal resource utilization. The supporting text provides an introductory overview of coal exploration, mining, and coalbed methane (CBM) development, followed by discussions on various megascopic aspects of coal geology (microscopic aspects are covered in Volume 2). Because of the vast subject matter, many generalities had to be made in the text. References are included to guide those interested to more detailed discussions. All citations within the document are linked to the detailed reference list for this volume. The overriding theme for this publication is that a picture is worth a thousand words.